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Yubomodule 8COLLAPSEReading the textbook for this chapter has helped me learn more about schizophrenia, the most complex of all mental illnesses and a serious, chronic, disabling disease of the brain. Before I read this chapter I did often classify schizophrenia and bipolar disorder together. But the truth is that schizophrenia is a much more serious brain disorder than bipolar disorder, which is a purely psychological disorder.Schizophrenia is a major human health hazard with an extremely high risk factor, and when the patient has an episode the mental world and the real world are torn apart, and the patient may cause serious harm to loved ones or to society. Moreover, schizophrenia was thought to be haunted by ghosts and spirits until the early twentieth century, when it was treated as a mental illness.I think schizophrenia should be more widely known by society and the general public than just from movies or fiction, and I think it suffers from the same thing as bipolar disorder in the realm of artistic creation, which is that both can be glorified. We should let the public know more objectively about this disease and seek medical attention as soon as possible when we notice symptoms in ourselves, as this is the most effective way to fight schizophrenia.

urs agoAngello discussion 8COLLAPSEI really liked this chapter as I got to learn a lot about schizophrenia such as the positive and negative symptoms. While I was reading this chapter on schizophrenia, I remembered reading an article on the racial disparities in the misdiagnosis of schizophrenia. African Americans are three to four times more likely to be diagnosed with schizophrenia compared to Euro-Americans. One reason for this was that African Americans were being misdiagnosed with schizophrenia. When African Americans are evaluated, their psychotic symptoms are overemphasized, and mood problems are given less attention. Meaning that if they’re undervaluing and not adequately assessing the presence of these mood symptoms, it can be easy to go to the next step on the diagnostic ladder and over-diagnose schizophrenia. This can be due to subconscious or unconscious racial bias affecting the diagnosis of schizophrenia.Some ways to combat these disparities in the misdiagnosis of schizophrenia, I’d suggest is to have a more planned diagnostic process through the greater use of the structured clinical interview, as this could help minimize misdiagnoses and racial bias. Individuals from a racial minority group also might feel mistrust when being assessed by someone from a racial majority group, which could affect how they act and how the clinician interprets symptoms. Thus, having a practitioner of the same racial group and having more diversity in mental health practitioners, could reduce bias and lead to more accurate diagnoses. Improving cultural competence training for providers and increasing public awareness of the problem of racial discrimination in mental health care could also reduce bias and lead to a more precise diagnoses.

Schizophrenia Spectrum and Other
Psychotic Disorders
CHAPTER
4
Chapter Outline
The Definition of Schizophrenia
Spectrum and Other Psychotic
Disorders
Living With Schizophrenia
Biological Causes of Schizophrenia
Psychosocial Causes of
Schizophrenia
Treatments for Schizophrenia
Copyright: karakoysya/Shutterstock.com.
From the Case of Lionel Aldridge
During the 1960s, the Green Bay Packers were the dominant team in professional football. Under the leadership of their legendary coach Vince Lombardi, they won three world championships and the first two Super Bowls.
Key to the Packers’ success was Lionel Aldridge, a defensive end who was a
stalwart of the Packers’ defense for almost a decade. Chosen as an All-Pro
and elected to the Green Bay Packers’ Hall of Fame, Lionel Aldridge was one
of the best ever to play his position.
Born in the bayou country of Louisiana on Valentine’s Day in 1941, Lionel
was raised by his grandparents until he was a teenager. They were poor, but
Lionel remembers his childhood as a normal and stable period of life. He
ultimately won a football scholarship to Utah State University. After college,
Lionel joined the Packers and helped them dominate professional football
throughout the 1960s. After retiring from football in 1973, Lionel began to
work in broadcasting.
But Lionel Aldridge’s life was slowly falling apart. One year after retiring from football, at age 33, he began to hear voices telling him that he was
a fraud and a con man and that his past would catch up with him. Lionel
heard the voices even while announcing sports on TV. He grew increasingly
After reading this chapter, you
will be able to answer the following key questions:
n What is schizophrenia, and how
are schizophrenia spectrum
and other psychotic disorders
categorized in the Diagnostic
and Statistical Manual of Mental
Disorders (DSM-5)?
n How does schizophrenia
typically develop and progress?
n What causes schizophrenia?
n What are the main treatments
used today to help people
with schizophrenia and related
disorders?
129
paranoid that people were out to get him, a fear that was magnified by his nightly appearance on TV, where all his “enemies” could see him. The voices told Lionel that his boss
was after him, that his wife was a witch, and that his dog was causing all his problems and
had to be killed. Then Lionel began to see things that were not there—the wind chased
him, the food on his dinner plate transformed itself into a mass of worms, and his children’s balloons became snakes trying to bite him.
There had been few, if any, warning signs of the disorder earlier in his life. In fact, he
had enjoyed a life of remarkable success. However, over the next several years, delusions
and hallucinations robbed Lionel of his grasp on reality. He was hospitalized more than
20 times during the 1980s with a disorder that left him impoverished and alone. His
condition would improve when he took his prescribed medications, but he so hated their
side effects (they left him unable to speak for hours at a time) that he often refused to take
them. Aldridge lost his job, his family, his financial security, and his home. He began to
live on the street, pawning his possessions, as he fought or ran from enemies he was sure
were surrounding him.
hallucination: A sensory
experience that seems real
but is not based on external
stimulation of the relevant
sensory organ.
delusion: An extreme, false
belief that is so firmly held that
no evidence or argument can
convince the person to give
it up.
What could make Lionel Aldridge and millions of other people around the world hear
voices, see visions, cower in terror, think that loved ones want to kill them, and retreat
into desperate solitude? What causes this devastating and bewildering condition, and how
can it be treated? This chapter examines the current knowledge about schizophrenia, a
psychosis that can impair almost all aspects of psychological functioning.
Clinicians employ differing definitions of psychosis, but in general, the term refers to a
serious mental disorder in which individuals lack an accurate perception or understanding
of reality and have little insight into how their behavior appears to others. A psychosis typically includes periods of hallucinations, sensory experiences that seem real to the person
but are not based on any external stimulation of the relevant sensory organ, and delusions,
false beliefs about reality that are so firmly held that no evidence or argument can convince the person to give them up. Often, psychoses also involve thinking and behavior
that are so jumbled and disorganized that onlookers conclude that the person is crazy or
insane. Several disorders are accompanied by one or more of these psychotic symptoms;
schizophrenia is often marked by the presence of many such symptoms at once.
In this chapter, we examine several disorders for which the presence of psychotic
symptoms is a defining feature, but our main focus is on schizophrenia. First, we discuss
how schizophrenia has been defined over the past 200 years, how the DSM-5 describes
it today, and how it differs from other psychotic disorders. Then we discuss the lives of
people afflicted with schizophrenia—who they are, how they are similar, and how they
differ. Next, we turn to an examination of the biological and psychosocial factors that
appear to contribute to the development of schizophrenia, followed by descriptions of the
treatments that are most effective in controlling the disorder.
The Definition of Schizophrenia Spectrum
and Other Psychotic Disorders
schizophrenia: A psychotic
mental disorder marked by
serious impairments in basic
psychological functions—
attention, perception, thought,
emotion, and behavior.
130
Schizophrenia is not, as popular culture sometimes suggests, a split or multiple personality, which, as described in Chapter 10, is called dissociative identity disorder. Instead,
schizophrenia is a psychosis that is marked by a fragmentation of basic psychological
functions—attention, perception, thought, emotion, and behavior—that are normally integrated to help us adjust to the demands of reality. People with schizophrenia misperceive what is happening around them, often hearing or seeing things that are not there.
They have trouble maintaining attention to the present environment, and their thinking is
often so confused and disorganized that they have difficulty communicating with others.
Some people with this disorder display a blunting of emotional feelings and a lack of
motivation that leaves them immobile and unresponsive. Or their emotions may be highly
Chapter 4 Schizophrenia Spectrum and Other Psychotic Disorders
inappropriate, including uproarious laughter at events that are not funny or uncontrollable
crying when nothing sad has taken place. Bizarre behavior is another common symptom,
sometimes involving an outlandish or disheveled appearance and odd mannerisms. In
other cases, the person avoids social contact as much as possible, withdrawing into private fantasy.
What holds this collection of symptoms together? Not all of them occur in all cases of
schizophrenia, and many of them are displayed by people with other disorders. Does it
make sense to talk about one disorder called schizophrenia? Or is schizophrenia a label
that is applied to several different disorders that should be viewed on a continuum? The
concept of schizophrenia is anything but simple, as its history shows.
The Evolving Concept of Schizophrenia
The first formal description that unequivocally matches the current conception of schizophrenia is over 200 years old (Gottesman, 1991). In 1809, the classic symptoms of schizophrenia were first documented in descriptions of patients written by John Haslam at London’s Bethlehem Hospital and by Philippe Pinel at Paris’s Bicetre (Gottesman, 1991).
Another 50 years passed before Belgian psychiatrist Benedict Morel grouped a constellation of symptoms into a description of a specific syndrome (Kolb, 1968). Morel described
the case of a previously bright 14-year-old boy whose intellectual and emotional abilities
gradually deteriorated until he lost all of his prior knowledge and many mental functions.
Morel called this condition demence precoce (or dementia praecox, in Latin), meaning
premature loss of rational thought.
By the late 1800s, dementia praecox and several related psychoses had been documented by a number of German psychiatrists. The most influential of this group was Emil
Kraepelin, a psychiatrist at Heidelberg Clinic who had examined thousands of mental
patients by the 1890s. Through his systematic observations, Kraepelin concluded that
three forms of psychosis were all variations or subtypes of a single syndrome that he
called dementia praecox. The subtypes were: (1) hebephrenia, in which the person behaved in a silly, immature, and disorganized manner; (2) catatonia, in which the person
held rigid, immobile postures and was mute for long periods; and (3) paranoia, in which
the person had delusions of grandeur or persecution. Later, Kraepelin added the simplex
or simple subtype, marked by gradual withdrawal and lack of responsiveness to the environment. Kraepelin differentiated these conditions from what he believed was the other
major mental disorder—manic depression (known today as bipolar disorder, as discussed
in Chapter 5). He thought that dementia praecox was a progressive, deteriorating disease
that terminated in “mental weakness” (Gottesman, 1991, p. 7).
By the beginning of the 20th century, however, Swiss psychiatrist Eugen Bleuler espoused different ideas. Bleuler recognized (as Kraepelin ultimately admitted) that dementia praecox did not always begin at an early age; therefore, the term praecox was not
always appropriate. Furthermore, some people with the disorder got better, so dementia
was not an appropriate description either. The central problem, said Bleuler, was a loosening or disharmony among various mental processes. There was a split (“schizen”) in
the mind’s (“phren”) normally integrated processes of mood and intellect, creating a condition he called schizophrenia (Bleuler, 1911/1950).
In his classic 1911 book, Dementia Praecox: The Group of Schizophrenias, Bleuler
categorized schizophrenia’s symptoms as either primary or secondary. According to
Bleuler, four primary symptoms are responsible for the split of mental functions:
1. loosening of associations, such that thoughts and ideas are not coherently linked;
2. ambivalence, wanting two contradictory things at once and being unable to choose
between them;
3. autism, or total self-centeredness in which reality is replaced by a fantasy life; and
4. affective disturbance, in which emotional responses are inconsistent with actions.
MAPS – Attempted Answers
These symptoms—known as Bleuler’s four As—force the person with this disorder
to try to adapt to a chaotic mental life. According to Bleuler, the adaptations—attempted
Chapter 4 Schizophrenia Spectrum and Other Psychotic Disorders
131
answers—lead to other common symptoms of schizophrenia: delusions, hallucinations,
mutism, and rigid postures.
Bleuler’s conception of schizophrenia broadened Kraepelin’s original criteria. By
Bleuler’s definition, a diagnosis of schizophrenia did not require early onset, continuous
deterioration, or hallucinations or delusions. Thus, compared with Kraepelin’s view of
the disorder, many more cases met Bleuler’s definition of schizophrenia. For example,
Lionel Aldridge in the chapter-opening case would not have satisfied Kraepelin’s criteria
for schizophrenia, but he did fit Bleuler’s more flexible conception of the disorder.
During the first part of the 20th century, Kraepelin’s definition of schizophrenia remained dominant among diagnosticians in Europe, while Bleuler’s ideas found favor in
North America. Over time, the two conceptualizations became increasingly divergent. A
landmark study comparing the practices of mental health professionals in New York and
London found that people who were diagnosed with schizophrenia according to North
American (Bleulerian) criteria were likely to be diagnosed with manic depression (bipolar disorder), major depression with delusions, or neurosis by British clinicians (Cooper et
al., 1972). Obviously, such differences in diagnosis hindered communication and reduced
the comparability of research by North American and European scientists.
Partly to resolve this discrepancy, American mental health professionals began to search
for an approach that would allow an operational definition of schizophrenia. The solution
was derived from the work of the German psychiatrist Kurt Schneider (1959), who believed that particular kinds of delusions and hallucinations were the “first rank” or defining
features of schizophrenia. Schneider’s first-rank symptoms were relatively easy to observe and agree on; however, he ignored the quieter features of schizophrenia that are now
known to also be important (Andreasen & Carpenter, 1993). A synthesis of the definitions
of Kraepelin, Bleuler, and Schneider was eventually achieved in the DSM-III and remains
the basis for the DSM-5 definition. The DSM-5 eliminated the clinical subtypes (e.g., paranoid) formerly used to organize the vast heterogeneity of the disorder because they were
invalid (Tandon et al., 2013). Yet, it still is not understood why schizophrenia presents so
differently in so many people and whether it is truly a single disorder (Paris, 2013).
Schizophrenia According to the DSM-5
According to the DSM-5, the presence of any one symptom of schizophrenia is not
enough to diagnose the disorder. Rather, as Table 4.1 shows, there are several characteristic psychotic symptoms, some combination of which must be present for a diagnosis,
with at least one of the symptoms being a delusion, hallucination, or disorganized speech.
Furthermore, the symptoms must have been active for a minimum of 1 month, along with
other signs of disturbance that have lasted for at least 6 months. These symptoms must be
TABLE 4.1 The DSM-5 in Simple Language: Diagnosing Schizophrenia
Schizophrenia is diagnosed when a person shows at least two of the following five
symptoms for over a month, with some symptoms lasting 6 or more months:
1. false beliefs (delusions),
2. false perceptual experiences (hallucinations),
3. hard-to-understand speech (e.g., loss of train of thought, sentences only
loosely connected in meaning),
4. unusual behavior (in which the individual acts in any number of ways—from
silly and childlike to angry and aggressive—and has inappropriate moods) or
catatonic behavior (in which the individual is unresponsive to external stimuli
with disturbances in movement from immobility to excessive activity), and
5. negative symptoms (decrease or absence of normal function, such as social
withdrawal, sloppiness of dress and hygiene, and loss of emotion, motivation,
or judgment).
Source: Adapted from American Psychiatric Association (2013a).
132
Chapter 4 Schizophrenia Spectrum and Other Psychotic Disorders
accompanied by marked deterioration in the person’s ability to function at work, engage
in social relationships, and maintain self-care, and they must not be due to another mental
disorder, substance abuse, or a medical condition.
The symptoms of schizophrenia are often classified as either positive or negative.
Positive symptoms are distortions of normal psychological functions that produce excess
behaviors, such as hallucinations, delusions, bizarre behavior, confused thinking, and disorganized speech. (Obviously, the term positive in this context does not mean that these
behaviors are desirable, but rather that they are present in the lives of those with the disorder and are absent in those without schizophrenia.) Negative symptoms involve a diminution, absence, or loss of normal function; examples include apathy, flat emotions, lack
of self-help skills, and social withdrawal. Positive symptoms tend to respond to antipsychotic medications better than negative symptoms. As will be noted later in this chapter,
there is some evidence that positive and negative symptoms might have different causes.
Positive Symptoms of Schizophrenia
Most people with schizophrenia exhibit both positive and negative symptoms at one time
or another. Although a greater number of negative symptoms suggests a worse overall
prognosis, positive symptoms are often more bizarre and therefore more immediately noticeable, even frightening, to observers. The two hallmark symptoms of schizophrenia—
delusions and hallucinations—are discussed in detail next, along with other positive
symptoms of the disorder.
Delusions Delusions are present in about 90% of people with schizophrenia and 66%
of people with bipolar disorders during acute episodes (Baethge et al., 2005). Usually,
delusions involve misinterpretations of normal perceptual experiences. In other words, a
person experiences the world as others do but forms obviously incorrect interpretations
of those experiences. For example, if a police officer waves to pedestrians at a busy street
corner, delusional individuals might interpret this not as a sign to cross the intersection,
but as a signal to a would-be assassin, suggesting a deficit in their ability to infer the actions of others (Ozguven et al., 2010). Explanatory delusions are likely related to the misinterpretation of sensory events, such as a hallucination. In other words, the delusion is an
attempted solution—a way for individuals to make sense of their unusual and confusing
sensory experiences. Another possibility is that the delusion functions to increase the
person’s meaning in life; Roberts (1991) found that people with systematized delusions
possessed more favorable contents to their beliefs than a comparison group.
The range of beliefs that may constitute a delusion is quite broad. Flagrant, bizarre delusions are fairly easy to identify. Truly implausible beliefs—for example, that a person’s
heart has been removed by aliens or that Brian Williams is spying on a person’s home
every time he broadcasts the evening news—are easily recognized as delusions. But in
other instances, distinguishing a delusion from a mistaken belief can be difficult. A Division II college athlete’s belief that he can become a professional athlete runs contrary
to much of the evidence, but it is not so extreme that it would be considered delusional.
Generally, the clinician tries to determine whether a given belief is odd enough to qualify
as a delusion, which usually depends upon how strongly held the belief is, particularly in
the face of contradictory evidence.
Religious beliefs that are not endorsed by a clinician’s culture or that are not familiar
to the clinician may present particular diagnostic problems. Are such beliefs delusional or
just rare conclusions accepted as the truth by a group with different cultural beliefs and
practices? Most Westerners consider beliefs in the healing powers of witch doctors to be
misguided, but many groups endorse such beliefs, and it would typically be improper to
label them delusions. Usually, a delusion can be distinguished from a false belief on the
basis that the delusion is recognized by almost everyone in a given society as obviously
false.
Some delusions are classified by specific content. For example, in somatic delusions,
people believe that something is wrong with their bodies. They may be convinced that
they are infested with parasites or that they are being bombarded with poisonous rays.
positive symptoms: Symptoms
associated with schizophrenia,
involving distorted or
excess behaviors, such as
hallucinations, delusions,
bizarre behavior, confused
thinking, and disorganized
speech.
negative symptoms:
Symptoms associated with
schizophrenia, involving a
diminution, absence, or loss
of normal psychological
functions; examples include
apathy, flat emotions, lack
of self-help skills, and social
withdrawal.
MAPS – Attempted Answers
MAPS – Prejudicial Pigeonholes
Chapter 4 Schizophrenia Spectrum and Other Psychotic Disorders
133
Source: Cartoonresource/Shutterstock.com.
In other cases, a man may believe he is losing his penis, or a woman may be convinced
she is pregnant, despite clear evidence to the contrary.
Delusions of persecution, the most common delusions in schizophrenia (Appelbaum,
Robbins, & Roth, 1999), are beliefs that the person is being tormented or harassed by
an individual or group such as the FBI, a foreign government, or extraterrestrials. Lionel
Aldridge’s belief that enemies were tracking him while he was on TV was a persecutory delusion. These delusions lead the person to always be on guard, lest an enemy sneak up undetected. Ambiguous events are usually interpreted in the most threatening terms. For instance,
Aldridge’s false belief that his wife was a witch may have been strengthened whenever he
saw her cooking soup on the stove, as he may have interpreted that as a witch’s potion.
Delusions of reference are also relatively common and occur when people misinterpret
sounds or other stimuli as having special reference only to them. For example, static
from a radio may be interpreted as a sign that someone is trying to communicate with the
listener. A newspaper article about a celebrity’s troubles may be viewed as an exposé of
a personal foible. Delusions of reference may also be triggered by highway billboards,
song lyrics, and movies.
Delusions of control involve beliefs that an enemy or foreign entity is controlling a
person’s thoughts, feelings, or behavior. One individual was convinced that his mind was
Connections
manipulated by deceased relatives who were living on Jupiter and “controlling earth’s
Are delusions an excuse
equipment as well as its people.” Another believed that a dentist had implanted a microfor criminal behavior? For
chip in his tooth, causing his bowels to lock up (Brown & Lambert, 1995). Related dea discussion of the relalusions include thought withdrawal, the belief that thoughts are being stolen out of a
tionship between legal
person’s brain; thought insertion, the belief that bad thoughts are being forced into the
concepts of responsibility
and mental disorders, see
delusional person’s head; and thought broadcasting, the belief that a person’s thoughts are
Chapter 17.
being transmitted so that others can hear them.
People displaying delusions of grandeur believe that they are famous or important,
often someone who can save the world from famine or war. These delusions are also common in bipolar disorders (see Chapter 5’s opening case). Religious themes are prominent
in many delusions of grandeur. Perhaps the most famous example occurred in the 1960s,
when three male patients at different mental hospitals in Michigan all claimed to be Jesus
Christ. Ultimately, they were transferred to the same ward of a state hospital in Ypsilanti,
Michigan, where they lived together for 2 years. Their encounters are described in Milton Rokeach’s classic book The Three Christs of Ypsilanti (1964). In the book, the three
men are referred to by the fictitious names of Clyde, Joseph, and Leon. They met for the
first time on July 1, 1959, in a small room at the Ypsilanti State
Hospital. According to Rokeach, the first meeting began with a
round of routine introductions. After giving his real name, Joseph
was asked if there was anything else he wanted to tell the group.
“Yes, I’m God,” he replied. Clyde introduced himself next, also
giving his straight name first, and then proceeding, “I have six
other names, but that’s my vital side and I made God five and
Jesus six . . . I made God, yes. I made it 70 years old a year ago.
Hell! I passed 70 years old.” Last came Leon.
“Sir,” Leon began, “it so happens that my birth certificate
says that I am Dr. Domino Dominorum et Rex Rexarum, Simplis
Christianus Pueris Mentalis Doktor. [This is all the Latin Leon
knows: Lord of Lords, and King of Kings, Simple Christian Boy
Psychiatrist.] It also states on my birth certificate that I am the
reincarnation of Jesus Christ of Nazareth, and I also salute, and I
want to add this. I do salute the manliness in Jesus Christ also because the vine is Jesus and the rock is Christ, pertaining to the penis and testicles; and it so happens that I was railroaded into this
place because of prejudice and jealousy and duping that started
There are different types of delusions. In a delusion
before I was born, and that is the main issue why I am here. I want
of grandeur, individuals have a false belief that helps
to be myself. I do not consent to their misuse of the frequency
them seem better or more important than they are.
134
Chapter 4 Schizophrenia Spectrum and Other Psychotic Disorders
of my life.” When asked “Who are ‘they’ that you are talking about?” Leon responded:
“Those unsound individuals who practice the electronic imposition and duping. I am
working for my redemption. And I am waiting patiently and peacefully, sir, because what
has been promised to me I know is going to come true. I want to be myself; I don’t want
this electronic imposition and duping to abuse me and misuse me, make a robot out of
me. I don’t care for it.”
As this first session wound down, Clyde and Joseph became very annoyed, each believing the other was an imposter, each shouting divine warnings and orders to the other.
Leon, who had sat quietly throughout much of the diatribe, announced that he was not
coming back to any more meetings, which he claimed were “mental torture.” However,
the very next day, when Rokeach told the men it was time to get together again, they all
assembled in the same room without the slightest protest. This went on for 2 years, and
none of the men relinquished his delusional identity in that time period.
illusion: The misperception
or misinterpretation of actual
sensory experiences.
Chapter 4 Schizophrenia Spectrum and Other Psychotic Disorders
Source: Cartoonresource/Shutterstock.com.
Hallucinations It is important to distinguish hallucinations from illusions, which are
more common. Illusions occur when an actual sensory experience is misperceived or misinterpreted; the “man in the moon,” for example, is an illusion, not a hallucination; likewise, mistaking a cat’s meow for a human voice is an illusion. Hallucinations should also
be distinguished from a range of unusual experiences that occur among mentally healthy
people (Holroyd, Rabins, Finkelstein, and Lavrisha, 1994). After driving for an extended
time without sleep, for example, people might begin to see things swimming in front of
their eyes, or if they are alone in a strange building, they might easily be convinced that
they hear noises that are not there. Unusual sensory experiences such as these are not considered hallucinations unless the person acts as if they are real, is unable to stop them, and
reports that they persist no matter what the person does (Bentall, 1990; Heilbrun, 1993).
Hallucinations are characteristic of schizophrenia and occur in all modalities (Goghari,
Harrow, Grossman, & Rosen, 2013). Hallucinators have difficulty discriminating between
real events and their own subvocalizations, thoughts, daydreams, or mental images. They
often misattribute these sensations to external sources; therefore, hallucinations give
people the “illusion of reality” that seems to exist outside of their control. Baethge and
colleagues (2005) examined the past-week prevalence of hallucinations in 4,972 hospitalized psychiatric patients and found that hallucinations were most common in the patients
with schizophrenia, compared to those with other mental disorders. Sixty-eight percent of
the people with schizophrenia were hallucinating, as compared to 11–23% of the people
with bipolar disorders (depending upon the nature of the mood disorder) and 6% of the
people with depression. Hallucinations were also more severe and less treatment responsive in the people with schizophrenia. Auditory-verbal hallucinations were the most common, being experienced by 75% of the people with schizophrenia. Prevalence rates vary,
however, depending upon the sample (e.g., inpatient versus outpatient and cultural group;
Ndetei & Vadher, 1984; Thomas et al., 2007), rating period (e.g., lifetime versus current),
and grouping of modalities, with visual hallucinations typically reported to be the second
most common in schizophrenia (Langdon, McGuire, Stevenson, &
Catts, 2011). Across several studies, auditory hallucinations have
been estimated in 47–98%, visual hallucinations in 14–69%, and
other modalities (including somatic, olfactory, and gustatory) in
4–25% of people with schizophrenia (Langdon et al., 2011).
Auditory hallucinations, which usually involve hearing hallucinated voices, are the most common and often include content
that is negative or abusive (Copolov, Mackinnon, & Trauer, 2004).
Typically, the voices accuse the person of wrongdoing, belittle the
person, or command the person to perform some act (as they did
with Lionel Aldridge in the chapter-opening case). At times, two
or more voices may seem to be conversing about the person, as
was the case with Mark, a client who reported hearing the voices
of a man, a woman, and a child, all telling him that he was Harry
Truman and that he was responsible for killing thousands of
135
Japanese people. They warned him that if he “was ever out of his house after 11 P.M.,” he
would be set on fire and burned to death. The voices usually taunted him, saying, “go out
and burn,” “come take your turn” over and over again. Most people with schizophrenia
report that their voices are negative in content (53%), with 17% mixed and 27% neutral;
no voices are described as having positive content only (Close & Garety, 1998). The type
of perceived threat from the voice can vary greatly from one voice hearer to the next, and
many people employ a range of “safety-seeking” behaviors designed to mitigate threats
from malevolent voices. These safety-seeking behaviors are associated with beliefs about
the voice (e.g., whether it is harmful, all-powerful, or all-knowing) and include things like
hypervigilance, avoidance, compliance, or prayer (Hacker, Birchwood, Tudway, Meaden,
& Amphlett, 2008).
Visual hallucinations are experienced in about one third of cases of schizophrenia.
They usually involve visions of people or faces, although less distinct figures, objects,
or flashes of light may be experienced as well. One person with schizophrenia reported
seeing a computer screen behind her that displayed orders from her “higher in command”
to audit the tax forms of her high-school classmates. A common visual hallucination involves the faces of devils and demons, who may also serve as the sources of hallucinated
voices (Brewerton, 1994). It was originally thought that visual hallucinations were infrequent for those living with schizophrenia. However, recent evidence suggests that these
symptoms are more common than originally believed, particularly in those on the more
severe side of the spectrum of schizophrenia (Goghari et al., 2013).
Depending on the study, up to a fourth of people with schizophrenia report somatic
hallucinations, in which the person feels bizarre sensations within the body—such as
electricity shooting through the limbs. The most common forms of somatic hallucinations
are tactile—for instance, feeling like bugs or other things are crawling under or on the
skin (also known as formication). Actual physical sensations stemming from medical
disorders (perhaps not yet diagnosed) and somatic symptom preoccupations with normal
physical sensations (see Chapter 11) are not thought of as somatic hallucinations. Gustatory (taste) and olfactory (smell) hallucinations are less common experiences in people
with schizophrenia, but they almost always have an unpleasant character. One person
reported that he knew his food had been poisoned because he could taste arsenic in it.
Others claim that their flesh smells as if it were rotting. Taste and smell hallucinations
are more frequently seen in medical diseases, such as epilepsy, migraines, or Parkinson’s
disease, rather than mental disorders like schizophrenia.
formal thought disorder:
Symptoms involving
disturbances in the way
thinking is organized.
136
Disordered Thought Processes Whereas delusions are disturbances in the content of
thoughts, other positive symptoms of schizophrenia involve fundamental disturbances in
the form of thought—in how thoughts are organized, controlled, reasoned, and processed
(So et al., 2012). Almost all experts on schizophrenia agree that this formal thought
disorder is also a key feature of the disorder. In fact, a meta-analysis comparing the cognitive performance of those with and without schizophrenia across multiple studies found
that those with schizophrenia had significantly lower cognitive performance, suggesting
that cognitive deficits in general are features of the disorder (Heinrichs, 2005). Because
clinicians cannot directly observe how people think, however, they must infer thought
processes from how people communicate through speech. Therefore, the DSM-5 focuses
on the presence of disorganized speech as evidence of formal thought disorder.
In thought disorder, which is present in 80–90% of people with schizophrenia during
acute phases (Marengo, Harrow, & Edell, 1993), the speaker cannot maintain a specific
train of thought. While conversing or answering a question, the person “slips off track,”
leaving the listener trying to follow a wandering stream of talk. Such speech makes little
or no sense and has consequently been called derailment, cognitive slippage, or loosening
of associations. At extreme levels, speech becomes a word salad, in which words seem
to be mixed, tossed, and flung out at random. The following excerpt from the comments
of a person with schizophrenia illustrates some of the common characteristics of this
disordered speech:
Chapter 4 Schizophrenia Spectrum and Other Psychotic Disorders
Source: Cartoonresource/Shutterstock.com.
If things levels in regards and “timed” to everything: I am referring to a previous document when I made some remarks that were
also tested and there is another that concerns my daughter has a
lobed bottomed right ear, her name being Mary Lou. . . . Much
of abstraction has been left unsaid and undone in this product/
milk syrup and others, due to economics, differentials, subsidies,
bankruptcy, tools, buildings, bonds, national stocks, foundation
crap, weather, trades, government in levels of breakages and fuse
in electronics too all formerly “stated” not necessarily factuated.
(Maher, 1968, p. 395)
Although most of the words in this passage are familiar, their
arrangement does not make sense or communicate clear meaning.
People with schizophrenia often show little awareness that they
cannot be understood when speaking this way. Another sign of
disordered thought processes is the creation of words, or neologisms, the meaning of which appears to be known only to the
speaker. Two neologisms are italicized in the following example:
The players and boundaries have been of different colors in terms
of black and white, and I do not intend that the futuramas of supersonic fixtures will ever be in my life again because I believe that all known factors
that would have its effect on me even the chemical reaction of ameno [sic] acids as they
are in the process of combustronability are known to me. (Maher, 1968, p. 395)
Disordered thought processes may also be revealed through perseveration, in which
the person seems to get stuck on a word or concept and repeats it over and over. Another
sign of disordered thought is the presence of clang associations—words that are spoken
apparently only because they sound alike.
Whereas delusions and cognitive deficits are distinct, they influence each other in that
inaccurate cognitions increase or strengthen the central beliefs of delusions. In a study
of 300 people with at least two psychotic episodes, having a strong conviction related to
delusional beliefs, jumping to conclusions, and having less belief flexibility were distinct
cognitive constructs (So et al., 2012). Forty-one percent of the sample had 100% conviction in their delusions, and 50% showed a jumping-to-conclusions bias. In addition,
50–75% showed a lack of belief flexibility, which was inversely related to delusional
conviction (i.e., less belief flexibility meant stronger endorsement of one’s delusions).
Whereas cognitive deficits are clearly a part of schizophrenia, cognitive abilities do not
appear to deteriorate over time (Heaton et al., 2001), although they also do not improve
in response to medication or psychological therapy (So et al., 2012).
Disordered Behavior Another class of symptoms associated with schizophrenia is disorganized behavior that makes it impossible for individuals with schizophrenia to get
dressed properly, prepare food, or take care of other daily needs. These people may also
giggle or sob inappropriately or uncontrollably. Inappropriate sexual behavior, such as
masturbating in public, is not uncommon. Some less dramatic behavioral anomalies associated with schizophrenia include facial grimaces, lip smacking, and other stereotyped
behavior. One older male client would stuff all his pockets with magazine advertisements
of attractive female models, while repeating again and again, “Oh, so that’s what I’m
doing.” By the end of each day, so much ink from the magazines had rubbed off on him
that his clothes were filthy.
In addition to strange behavior, people with schizophrenia may also make peculiar
movements, hold themselves in contorted postures, walk in a peculiar fashion, and make
absurd or obscene gestures. The most dramatic behaviors range across a dimension of
catatonia. At one end of this dimension, the person becomes virtually immobile, maintaining an awkward body position for hours at a time. At the opposite extreme of catatonia, people may display great excitement, extreme motor activity, repetitive gestures and
catatonia: A dimension of
disordered behavior ranging
from immobility (where a
person may maintain awkward
body positions for hours at
a time, appearing stuporous)
to great excitement, extreme
motor activity, repetitive
gestures or mannerisms, and
undirected violent behaviors.
Chapter 4 Schizophrenia Spectrum and Other Psychotic Disorders
137
mannerisms, and undirected violent behaviors (Kleinhaus et al., 2012). In the DSM-5,
catatonia is a specifier of schizophrenia, meaning that a diagnosis of schizophrenia with
catatonia is given when this symptom is present; this decision was based on evidence that
there are different risk factors for schizophrenia with and without catatonia (Kleinhaus
et al., 2012). Over the past few decades, catatonic symptoms have occurred less often
with schizophrenia and more often in mood disorders (Stompe, Ortwein-Soboda, Ritter,
Schanda, & Friedmann, 2002; Taylor & Fink, 2003). This has lead experts to question
whether catatonia is necessarily a core symptom of schizophrenia or rather a behavioral
pattern that can occur in the context of several disorders, including neurodevelopmental
(see Chapter 3), bipolar (Chapter 5), and depressive disorders, as well as other medical
conditions, such as autoimmune or paraneoplastic disorders (American Psychiatric Association, 2013a). Catatonia prevalence rates vary from 1–32%, depending on diagnostic
criteria used, but current estimates put the occurrence of catatonic signs in psychiatric
patients at about 7–15% (Kendurkar, 2008; Sayegh & Reid, 2010).
anhedonia: Loss of the ability
to enjoy activities central to a
person’s life.
flat affect: Blunted emotional-
ity, often consisting of minimal
eye contact, an emotionless
face, little or no tone in the
voice, and a drab or listless
demeanor.
Negative Symptoms of Schizophrenia
Negative symptoms of schizophrenia contribute substantially to the morbidity and functional impairment seen in people with the disorder (Fervaha, Foussias, Agid, & Remington, 2014). These symptoms include social withdrawal, anhedonia (the inability to enjoy
almost anything, as discussed in Chapter 6), flat affect (empty mood), alogia (diminished
speech output), and avolition (no motivation). About a fourth to a third of people with
schizophrenia present during an acute episode with primary negative symptoms, meaning
that the symptoms are due to the disorder itself rather than to some other cause (Chang et
al., 2011; Mäkinen, Miettunen, Isohanni, & Koponen, 2008). Even after taking medication, one or more negative symptoms were present in 57.6% of people with schizophrenia, with primary negative symptoms in 12.9% (Bobes, Arango, Garcia-Garcia, & Rejas,
2010). The most frequent negative symptoms were social withdrawal (45.8%), emotional
withdrawal (39.1%), poor rapport (35.8%), and flat affect (33.1%; Bobes et al., 2010).
Flat Affect Many people with schizophrenia often stare straight ahead with an empty
or glazed look (54% in one study of hospitalized patients; Selten, Wiersma, & van den
of schizophrenia involving
Bosch, 2000). Even when spoken to, they make no eye contact with the speaker. Their
the failure to say much, if
faces are like emotionless masks. Their facial muscles appear slack, and they often speak
anything, in response to
questions or comments.
in a voice so toneless it sounds robotic. Their entire demeanor is drab and listless. This
flat affect or diminished emotional expression is one of the more
obvious negative symptoms of schizophrenia. Flat affect is an important symptom because it often suggests a poor prognosis.
Why does flat affect lead to exacerbation of schizophrenia?
Much research over the last decade has investigated this very
question. In one study, people with schizophrenia were compared
to controls with regard to their emotional processing (Gur et al.,
2006). More-prominent flat affect was associated with worse past
and current quality of life. Overall, those with schizophrenia were
less able to identify happy and sad emotions, and were less able
to identify changes in the intensity of these emotions. Flat affect,
above and beyond other negative symptoms of schizophrenia,
predicted poor performance with emotional processing. Not beThe negative symptoms of schizophrenia—including
ing able to identify the emotions in others or the intensity of those
social withdrawal, apathy, and dulled emotions—are
emotions has critical implications, particularly related to interperamong its most disabling features. Suicide attempts,
sonal interactions and relationships, increasing the morbidity for
although not officially listed as a negative symptom
those living with schizophrenia.
of schizophrenia, are a frequent complication of the
Source: dabjola/Shutterstock.com.
alogia: A negative symptom
disorder. Among people with schizophrenia, suicide
is the leading cause of premature death, occurring in
approximately 10% of individuals with the disorder
(Bromet, Naz, Fochtmann, Carlson, & TanenbergKarant, 2005).
138
Alogia The failure to say much, if anything, in response to questions or comments is called alogia. This negative symptom is
present in about half of hospitalized patients with schizophrenia
(Selten et al., 2000). People with alogia do not appear especially
Chapter 4 Schizophrenia Spectrum and Other Psychotic Disorders
negativistic; they just seem to have little to say. Trying to talk with a person who is alogic
often leaves a person wondering, “Is that all there is?” In other people, alogia takes the
form of slow or delayed responses that become so frustrating that people finally give up
trying to sustain the conversation.
Avolition The behavioral counterpart to alogia is avolition. Avolitional people may simply sit for hours on end, making no attempt to do anything. If they do begin some activity,
they often wander off in the middle of it, seeming to lose interest or to forget what they
were doing.
Avolition is present in over 90% of hospitalized patients with schizophrenia (Selten
et al., 2000) and is often accompanied by social withdrawal and anhedonia. People may
stare blankly at a television or become agitated by a hallucination, but otherwise, they
seem to lack any capacity to be engaged by the environment. Sensitivity to painful stimulation and recognition that another person is experiencing pain is even reduced in some
cases. People living with schizophrenia show less of an ability to detect and categorize
their own pain or pain in others when presented with a sequence of videos of pain-inducing events (Wojakiewicz et al., 2013). Thus, negative symptoms such as avolition result
in severe deficits in fundamental human processes, ranging from engagement in social
activity to pain detection.
avolition: A negative symptom
of schizophrenia in which
patients may sit for hours,
making no attempt to do
anything.
Distinguishing Schizophrenia From Other Psychotic Disorders
Before diagnosing schizophrenia, a clinician should consider other possible sources of the
symptoms observed as part of what is termed a differential diagnosis (i.e., a list of disorders that might fit the symptom profile). As noted in Chapters 5 and 6, for example, severe
mood disorders can produce some of the symptoms described here. Psychotic symptoms
can also be produced by intoxication from alcohol or other drugs and by several medical
conditions. For instance, hallucinations and delusions can result from Huntington’s disease, multiple sclerosis, central nervous system infections, endocrine disorders such as
hypo- or hyperthyroidism, metabolic disorders such as hypoglycemia, and liver or kidney
disease (American Psychiatric Association, 2013a). In these cases, the disorder is classified as psychotic disorder due to another medical condition.
Clinicians also need to consider the symptoms of schizophrenia on a spectrum of number and severity of symptoms. Some disorders are schizophrenia-like, but they do not meet
all the diagnostic criteria for schizophrenia, and they tend to be less severe. A common
disorder considered on the spectrum of schizophrenia includes schizotypal personality disorder, discussed further in Chapter 16. Spectrum disorders also include several disorders
classified by the DSM-5 as other psychotic disorders: delusional disorder, brief psychotic
disorder, schizophreniform disorder, and schizoaffective disorder. Most of these disorders
are relatively rare, and research on their characteristics and causes is scant. Their symptoms are usually more limited in duration and less intense than those of schizophrenia.
Delusional Disorder
People who display a rare form of psychosis known as delusional disorder show only
minimal impairment in their daily life apart from the presence of at least one delusional
belief. Usually, the delusion is persistent and causes these individuals to organize much
of their life around it. Other than the delusional belief and its consequences, though, these
individuals do not display odd or bizarre behavior. Perhaps for this reason, and because
these people usually avoid clinicians, this disorder tends to be diagnosed later in life than
schizophrenia. Table 4.2 describes the main subtypes of delusional disorder.
Brief Psychotic Disorder
“Nervous breakdown” and “falling to pieces” are familiar phrases used to describe people
whose psychological functioning has rapidly deteriorated, usually after they have experienced a severe stressor. These cases are best described by what the DSM-5 classifies as
brief psychotic disorder.
psychotic disorder due to
another medical condition:
A mental disorder involving
psychotic symptoms caused by
a medical illness or condition.
other psychotic disorders:
A group of mental disorders
whose psychotic symptoms
are usually more limited in
duration and less intense
than those of schizophrenia;
includes schizophreniform
disorder, schizoaffective
disorder, delusional disorder,
and brief psychotic disorder.
delusional disorder: A mental
disorder in which the main
symptom is the presence of at
least one systematic delusional
belief.
Chapter 4 Schizophrenia Spectrum and Other Psychotic Disorders
139
TABLE 4.2 Subtypes of Delusional Disorder
Subtype
Description
Typical Behaviors
Erotomanic
Individuals believe that some other person,
typically someone of notoriety or higher
status, is secretly in love with them.
Stalking the love object, sending annoying texts
or gifts, making unwanted phone calls, or taking
other steps to contact the loved object (such as the
woman who insisted that she was the secret lover of
David Letterman)
Jealous
Individuals believe that their romantic
partners are being unfaithful, despite very
little evidence.
Following the partner or constantly checking on
the partner’s whereabouts through phone calls or
repeated demands for the partner’s attention
Grandiose
Individuals believe that they have a special
talent, have made an important discovery,
know someone of great importance, or have
a special relationship with God beyond that
associated with established religion.
Trying to convert others into followers or provoking
confrontations with authorities (such as David
Koresch, leader of the Branch Davidian sect)
Persecutory
Individuals believe that they are being spied
on, cheated, followed, or otherwise taken
advantage of.
Becoming increasingly isolated and bitter, often
trying to bring about opportunities to fight their
alleged persecutors or to obtain legal remedies for
problems
Somatic
Individuals hold beliefs about their bodies,
such as the delusion that a rancid odor
is seeping out, that their ears are grossly
misshapen, or that they have foreign
organisms under the skin.
Becoming preoccupied with hiding the defect or
hypersensitive to signs that someone else has
noticed it
brief psychotic disorder:
The sudden onset of psychotic
symptoms marked by intense
emotional turmoil and
confusion.
postpartum onset: Beginning
of a disorder shortly after
giving birth.
schizophreniform disorder:
A disorder in which people
experience symptoms of
schizophrenia for only a few
months.
schizoaffective disorder:
A mental disorder in which the
person displays symptoms of
both schizophrenia and a mood
disorder without satisfying
the full criteria for either
diagnosis.
140
Unlike most cases of schizophrenia, brief psychotic disorder is characterized by the
sudden onset of an episode marked by intense emotional turmoil and confusion and the
appearance of positive psychotic symptoms, such as hallucinations, delusions, incoherent
speech, and catatonic or disorganized behavior. During this episode, the person is at high
risk for attempting suicide. By definition, the episode must last at least 1 day but less
than 1 month, after which the individual returns to a normal level of functioning. If the
symptoms last longer than 1 month, the diagnosis should be changed to one of the other
psychotic disorders.
Often, brief psychotic disorder is a reaction to a severe stressor, such as the death of a
loved one, but occasionally, no precipitating stressor can be identified. Whether a stressor
precipitated the symptoms is specified when making the diagnosis. Also, when brief psychotic disorder follows childbirth, it is specified as having a postpartum onset.
Schizophreniform Disorder
People who experience the symptoms of schizophrenia for only a few months are given
the diagnosis of schizophreniform disorder. There are two major differences between
schizophrenia and schizophreniform disorder. First, impaired social or occupational functioning is not required for a diagnosis of schizophreniform disorder. Second, in schizophreniform disorder, the symptoms are present for at least 1 but not more than 6 months.
About one third of people with schizophreniform disorder recover and go on to live without impairment in daily functioning or changes in mood; the other two thirds eventually
warrant a diagnosis of schizophrenia or schizoaffective disorder (Bromet et al., 2011).
Schizoaffective Disorder
In schizoaffective disorder, people display either hallucinations or delusions that resemble those experienced in schizophrenia, but during the same psychotic episode, the symp-
Chapter 4 Schizophrenia Spectrum and Other Psychotic Disorders
toms of a mood disorder are also present. However, to distinguish schizoaffective disorder from depressive or bipolar disorder with psychotic features, the individual must also
display delusions or hallucinations for 2 weeks in the absence of a major mood disorder.
Whereas interruption in daily functioning may be present, it is not a defining characteristic of the disorder. Therefore, the prognosis for schizoaffective disorder is generally better
than for schizophrenia but worse than for mood disorders. Unfortunately, the presence of
depressive symptoms increases the risk for suicide (Hor & Taylor, 2010). Schizoaffective
disorder is less prevalent than schizophrenia and is more often diagnosed in females than
in males (Malhi, Green, Fagiolini, Peselow, & Kumari, 2008).
Substance-Induced Psychotic Disorder
Hallucinations and delusions can result from ingestion of various substances, including
drugs of abuse (such as cocaine and cannabis), medications (such as corticosteroids), or
toxins (such as organophosphate insecticides). When people begin to experience hallucinations or delusions during or shortly after intoxication, exposure to, or withdrawal from
a substance, and the symptoms are not attributable to an episode of delirium (see Chapter
15), they qualify for the diagnosis of substance/medication-induced psychotic disorder.
In fact, many substances of abuse, including alcohol, nicotine, cannabis, and cocaine, have
been associated with schizophrenia onset—psychotic symptoms that persist for months after
the drugs have left the person’s system—and may be implicated in the causal mechanisms of
the disorder (Frisher, 2010; Jordaan & Emsley, 2014; Lieberman, Kinon, & Loebel, 1990).
Section Review
The current definition of schizophrenia evolved from:
n Morel’s original description, in the mid-1800s, of dementia praecox as a syndrome
marked by the premature loss of the ability to reason;
n Kraepelin’s identification, in the late 1800s, of dementia praecox as a major mental
disorder with several subtypes; and
n Bleuler’s broader definition of the disorder, which he named schizophrenia, because he viewed the splitting of psychological functions as the core of the problem.
Schizophrenia is a heterogeneous disorder in terms of its presentation, and its symptoms can be divided into two main categories:
n positive symptoms, which include delusions, hallucinations, disturbances in the
form of thinking, and disorganized and grossly inappropriate behavior; and
n negative symptoms, which include social withdrawal, anhedonia, flat affect, alogia,
and avolition.
Disorders associated with schizophrenia can be viewed dimensionally, based on:
n the type of symptoms present and the longevity of those symptoms;
n the presence of severe mood disorders; and
n intoxication from alcohol or other drugs.
substance/medication-induced
psychotic disorder: A
mental disorder in which a
person experiences psychotic
symptoms beyond what is
expected from intoxication or
withdrawal from a substance,
and in which the person is
not aware that the substance
is producing the psychotic
symptoms.
Living With Schizophrenia
Schizophrenia comes in many shapes and forms. It can appear suddenly, as it did with
Lionel Aldridge in the chapter-opening case, or it can develop slowly over several years.
It can affect teenagers, or it can first occur in people who are over 50. In some cases, the
most prominent symptoms are hallucinations or delusions; other people suffer primarily
from negative symptoms (Paris, 2013). Some people make a complete recovery, others
only partial, and roughly a fourth of people with schizophrenia continue to suffer symptoms of the disorder even when they take medications. Some remain hospitalized for
years, unimproved by any treatment. In truth, the term schizophrenia encompasses several disorders that vary dramatically in onset, number, type, and intensity of symptoms,
impairment, and prognosis (Paris, 2013). To highlight these differences, contrast the case
of Lionel Aldridge that begins this chapter with that of Louise:
Chapter 4 Schizophrenia Spectrum and Other Psychotic Disorders
141
Louise is a pale, stooped woman of 39 years, whose childlike face is surrounded by scraggly blond braids tied with pink ribbons. She was referred for a psychiatric evaluation
by her family doctor, who was concerned about her low level of functioning. Her only
complaint to him was, “I have a decline in self-care and a low life level.” Her mother says
that there has indeed been a decline that has occurred over many years. In the last few
months, Louise has remained in her room, mute and still.
Twelve years ago, Louise was a supervisor in the occupational therapy department of
a hospital, living in her own apartment, and engaged to a young man. After he broke off
the engagement, she became increasingly disorganized, wandering aimlessly in the street
and wearing mismatched clothing. She was fired from her job, and eventually, the police
were called to hospitalize her. They broke into her apartment, which was a shambles,
filled with papers, food, and broken objects. This hospitalization lasted 3 months, after
which Louise was discharged to her mother’s house.
Following discharge, her family hoped that Louise would pull herself together and
get back on track, but over the years, she became more withdrawn. She spent most of
her time watching TV and cooking with bizarre combinations of ingredients, such as
broccoli and cake mix, which she then ate by herself because no one else in the family
would. She hoarded stacks of cookbooks and recipes. Often, when her mother entered
her room, Louise would grab a magazine and pretend to be reading, when in fact she had
just been sitting and staring into space. She stopped bathing and brushing her hair or her
teeth. She ate less and less, although she denied losing her appetite, and over a period of
several years, she lost 20 pounds. She slept at odd hours.
On admission to the psychiatric hospital, Louise sat with her hands clasped in her lap
and avoided looking at the doctor who interviewed her. She answered questions and did
not appear suspicious, but her mood was shallow. She denied having depressed mood,
delusions, or hallucinations. However, her answers became odder as the interview progressed. In response to a question about her cooking habits, she replied that she did not
wish to discuss recent events in Russia. When discussing her decline in functioning, she
said, “There’s more of a take-off mechanism when you’re younger.” Asked about ideas of
reference, she said, “I doubt it’s true, but if one knows the writers involved, it could be
an element that would be directed in a comical way.” Between answers she repeated the
mantra, “I’m safe. I’m safe.” (Based on Spitzer, Gibbon, Skodol, Williams, & First, 1994)
Connections
What are the symptoms
of autism spectrum disorder? How do its suspected
causes differ from those
of schizophrenia? See
Chapter 3.
premorbid phase: The time
period before the prodrome,
in which it is possible to
identify delays in early
neurodevelopment (e.g.,
not meeting key pediatric
milestones) that may suggest
an increased risk of developing
schizophrenia in the future.
prodromal phase: The usual
first phase of schizophrenia
in which there is an insidious
onset of problems, suggesting
psychological deterioration.
142
The Course of Schizophrenia
Only about 4% of all diagnosed cases of schizophrenia develop before age 15. After that
age, the rate of onset increases rapidly, reaching a peak around the age of 25 (great news for
most college students!). The average age of people first admitted to a hospital because of
schizophrenia is about 30. Contrary to early views, schizophrenia can develop when people
are as old as 50–60 years, with about 23% of people living with schizophrenia experiencing
their first onset of symptoms after the age of 40 (Howard, Rabins, Seeman, & Jeste, 2000).
Recent conceptualizations of schizophrenia suggest that the disorder constitutes at
least three phases (Agius, Goh, Ulhaq, & McGorry, 2010): prodromal phase, active phase
(acute psychosis), and residual phase (chronic illness), although at times demarcation
between these phases is imprecise (Tandon, Nasrallah, & Keshavan, 2009). Recent biological research supports these phases, suggesting that schizophrenia may be a disorder of
both neurodevelopment and neurodegeneration (see the “Controversy” feature). In some
classifications, a fourth phase is described, called the premorbid phase, a time period
before any symptoms are present. Instead, this phase represents the genetic vulnerability
coupled with the environmental exposures that together confer risk for the disorder. Although the onset of symptoms of schizophrenia may begin abruptly, most cases start with
a prodromal phase, in which affected persons show an insidious onset of problems that
suggest that something is going wrong with them. They may start to avoid meals with
Chapter 4 Schizophrenia Spectrum and Other Psychotic Disorders
CONTROVERSY
Schizophrenia: An Appropriate Diagnostic Label or One in Need of Reconceptualization?
A significant amount of evidence supports the DSM-5
diagnostic category of schizophrenia. The diagnosis
does have characteristic symptoms, including positive,
negative, motor, mood, and cognitive symptoms that
are modestly responsive to antipsychotic medication
(Tandon, Keshavan, & Nasrallah, 2008). Also, there is
much evidence that schizophrenia is a valid diagnostic entity because the conceptualization of the disorder
across cultures is highly similar, and the interrater reliability of the diagnosis is high (Jakobsen, Frederiksen,
Parnas, & Werge, 2006), meaning that different clinicians would diagnose schizophrenia after assessing
the same person. Tandon and Maj (2008) argue that the
diagnosis itself is a seemingly parsimonious construct
that carries with it a wealth of information to society,
researchers, clients, and clinicians.
However, there is mounting evidence suggesting
that the current conceptualization of schizophrenia
does not come close to grasping the heterogeneity—
vast differences—in symptom presentation and course
that is repeatedly seen in research studies (Paris, 2013;
Tandon et al., 2009). Although there have been significant developments in determining potential causes of
the disorder, as presented later in this chapter, there is
yet to be a reliable biological model of schizophrenia
that adequately incorporates the different courses of
individuals living with it. For example, neurobiological
findings that have been discovered in one study with
one group of people living with schizophrenia have not
always been replicated in other cohorts.
One significant change that was made from the
DSM-IV to the DSM-5 suggests that the definition of
schizophrenia is changing. In the previous DSM, there
were a number of subtypes that could be diagnosed for
the purpose of attempting to account for the heterogeneity in symptom presentation. These included designations for disorganized cognitions and behaviors,
paranoia, and mood disturbances. In a large part because these subtypes were unstable over time (Helmes
& Landmark, 2003) and because their designation did
not help to differentiate treatment (Regier, 2007), they
were abandoned when the diagnosis was reviewed for
the current diagnostic manual.
Whereas this represents some progress in redefining this disorder, Tandon and colleagues (2009) suggest
that more changes are needed. For example, instead of
individuals being categorized by their most prominent
symptom, they could be evaluated across the multiple
symptom domains that are characteristic of the disorder because these are likely representative of related,
yet distinct, entities. Take the diagnosis of schizoaffective disorder. The characteristic features include a
mood disturbance along with psychotic symptoms.
There is also the possibility that one could have a major depressive disorder along with psychotic features.
Instead of considering two separate disorders, a new
method of understanding symptoms could include a
severity rating on the psychotic symptoms and then
the mood symptoms separately over the course of the
disorder. This would entail more of a dimensional rather
than an entirely categorical approach to diagnosis, as
discussed further in Chapter 16.
Tom Insel, a researcher at the National Institute of
Mental Health, has proposed that a new conceptualization should involve the view that schizophrenia is a
neurodevelopmental disorder (see Chapter 3). He argues that, given all of the evidence highlighting perinatal and adolescent risk for schizophrenia, the beginning
of severe symptoms in late adolescence to early adulthood should be seen as the later stage of the disorder,
rather than its onset (Insel, 2010). If schizophrenia is
viewed from a developmental perspective, with stages
of the disorder starting during infancy and early childhood, when particular factors arise that confer risk for
the disorder, then treatment efforts can be more targeted. Some researchers believe that it is only within
a new conceptualization of schizophrenia that we can
move more effectively toward its prevention.
Thinking Critically
1. Does removing the subtypes of schizophrenia
(e.g., paranoid schizophrenia) represent progress
in understanding the disorder or a step backward
in your view?
2. What do you think about the idea—for schizophrenia as well as for other mental disorders—of using
a dimensional (rating on each domain) rather than
categorical (you have a disorder or you do not)
approach to diagnosis?
3. Does it make sense to view schizophrenia as a
developmental disorder and look for early signs in
children? How could that help people?
their families or stop paying attention to their appearance and hygiene. Often, they start
to talk in unusual ways, behave just a little strangely, and seem easily irritated and frustrated, resulting in difficulties at school, work, or socially. As a general rule, the longer
this prodromal phase lasts, the poorer the prognosis.
Chapter 4 Schizophrenia Spectrum and Other Psychotic Disorders
143
Source: Cartoonresource.com.
Eventually, but usually after some crisis, prodromal symptoms progress to an active phase, sometimes called the
first-episode phase, in which one or more psychotic symptoms, such as delusions and hallucinations, break into the
open. The disorder appears most serious and obvious to other
people during this phase, as those living with the disorder
lose insight into the problems they are experiencing.
Following the active phase is a residual phase, during
which the psychotic symptoms subside in frequency and intensity; this is also referred to as the chronic or stable stage
of the disorder. This stage may resemble the prodromal
phase; individuals may be withdrawn and apathetic, behave
strangely at times, and continue to show social and occupational impairments that may result in a lower level of func“You know, Mr. Symes, you are not actually
tioning than even during the prodromal phase. There tend
a doctor. . . . You’re just in the active
to be peaks and valleys to the intensity of the symptoms,
phase of your schizophrenia right now so
depending upon engagement in treatment and psychosocial
you think that you work here.”
stressors present in the individual’s life.
Whereas it is helpful to think about the progression of schizophrenia in stages for treatactive phase (of
schizophrenia): The stage
ment purposes, it is just as important to acknowledge that the course of schizophrenia is
of schizophrenia during
highly variable and individualized. Clearly, schizophrenia does not inevitably result in
which one or more psychotic
permanent disability, although most people with schizophrenia continue to suffer recursymptoms, such as delusions or
ring symptoms. In some cases, the symptoms improve so that people can live almost comhallucinations, appear.
pletely on their own. In other cases, people improve for a while and then suffer a relapse
residual phase (of
in which the symptoms can be serious enough to require rehospitalization. Remission has
schizophrenia): A stage of
a reported rate of 17–78% in first-episode schizophrenia and 16–62% in people with mulschizophrenia during which
tiple episodes (AlAqeel & Margolese, 2012). The pattern of symptom exacerbation and
most psychotic symptoms have
de-escalation may be repeated several times, but as people age, they are hospitalized less
subsided in frequency and
often. The rate of rehospitalization in those over the age of 65 living with schizophrenia is
intensity; the affected person
about 19% but exceeds 28% in people ages 45–64 years, with a disproportionate number
may still be withdrawn and
apathetic, behave strangely
of rehospitalizations occurring in those with public (rather than private) health insurance
at times, and continue to
(Elixhauser & Steiner, 2013).
show social and occupational
An important study completing a 15- to 25-year follow-up of 644 people living with
impairments.
schizophrenia found that over half had favorable outcomes following the initial onset of
the disorder, with minimal symptoms, reasonable functioning, and employment (Harrison et al., 2001). A systematic review also supported the notion that outcome from
first-episode psychosis may be more favorable than previously reported, with 42% of
people experiencing good outcomes across 37 studies and 4,100 participants (Menezes,
Arenovich, & Zipursky, 2006). However, reaching functional recovery earlier in the onset
of the disorder is less common, with only about 14% of people recovering for more than 2
years in the first 5 years of the disorder (Robinson, Woerner, McMeniman, Mendelowitz,
& Bilder, 2004). Overall, a diagnosis of schizophrenia is associated with a poorer outcome than other diagnostic groups, such as mood disorders, and symptom patterns seem
to be stable over the course of the disorder (Lang, Kösters, Lang, Becker, & Jäger, 2013).
The variables most frequently associated with remission are better premorbid function,
milder symptoms at baseline (especially fewer negative symptoms), early response to
treatment, and shorter duration of untreated psychosis (AlAqeel & Margolese, 2012). As
it is evident that the course of schizophrenia is highly variable, it is essential to consider
who is more or less impacted by the disorder.
Who Is Affected by Schizophrenia?
Even though schizophrenia is less common than most other mental disorders in this textbook, it nonetheless has a huge impact in terms of disease burden, hospitalizations, and
even homelessness (see Chapter 17; Centers for Disease Control and Prevention, 2014).
Worldwide, about 51 million people suffer from schizophrenia, approximately 2.2 million
144
Chapter 4 Schizophrenia Spectrum and Other Psychotic Disorders
Source: Peter Hermes Furian/
Shutterstock.com.
of whom live in the United States (Narrow, Rae, Robins, &
Regier, 2002; Torrey, 2001). Annually, new cases arise at a rate
of 8 to 40 per 100,000 persons (McGrath et al., 2004), and at
any given time, 0.3–1.0% of the population has a diagnosis of
schizophrenia (Goldner, Hsu, Waraich, & Somers, 2002), with
a 0.7% lifetime risk of developing the disorder (Saha, Chant,
Welham, & McGrath, 2005).
Cultural Background
Does culture make a difference in the risk for schizophrenia?
Interest in this question dates back to the late 1800s, when
Kraepelin himself explored this issue by touring several coun- Syd Barrett (1946–2006) was a founding member of
tries to examine their mental patients. After traveling to Sin- the band Pink Floyd, whose classic album Dark Side
of the Moon had an album cover similar to the image
gapore, where he examined patients from Java, China, and shown here. Barrett was one of the most legendary
Malaya, Kraepelin concluded that their symptoms were re- rock stars to develop schizophrenia, likely triggered
markably similar to those of his patients in Germany. Such by significant drug use, as well as the stress and
experiences convinced Kraepelin that the disorder was trans- pressure of his career. Floyd classics such as “Shine
on You Crazy Diamond” and “Wish You Were Here”
mitted genetically and was universal.
The strongest support for the universality of schizophrenia were written as tributes to Barrett, who spent the last
3 decades of his life in a quiet cottage in Cambridge,
comes from a series of studies sponsored by the World Health England. Other famous cases of schizophrenia include
Organization (WHO) called the “International Pilot Study on Jack Kerouac, an American novelist at the forefront
Schizophrenia” (IPSS) and the “Determinants of Outcome of of the Beat Generation in the 1950s and 1960s,
Severe Mental Disorders” (DOSMD) (World Health Orga- and John Forbes Nash, Jr. (1928–), an American
nization, 1978). Beginning in the 1960s, these studies were mathematician and 1994 Nobel Prize winner. Nash is
conducted in 12 research centers in 10 countries: Denmark, the subject of the 2001 Hollywood movie A Beautiful
India, Nigeria, Columbia, Russia, China, Czechoslovakia, Ja- Mind. The film, loosely based on the biography of the
same name, focuses on Nash’s mathematical genius
pan, the United Kingdom, and the United States. The WHO and also his battles with schizophrenia.
studies reached several conclusions. First, the descriptions of
symptoms for people with schizophrenia in the various countries were similar; in fact, based on symptom patterns alone, it was not possible to identify
the country from which people were drawn (Jablensky et al., 1992)—a finding confirmed
by subsequent research (Crow, 2008). Second, the morbidity risk, defined as the risk morbidity risk: The risk
that a given person has of developing the disorder over his or her lifetime, averaged 1%. of individuals developing a
Third, at each site, the prevalence of schizophrenia (whether defined by broad or narrow disorder over their lifetime.
criteria) was significant. More recent research confirms these findings and even expands
them, suggesting that the prevalence rates of schizophrenia are stable across such factors
as culture, gender, religion, and geographic region (Jablensky, 1999).
However, other studies have found greater variation in schizophrenia prevalence than
those found by the initial WHO studies. For example, a study by Goldner, Hsu, Waraich,
and Somers (2002) determined that, particularly in Asian countries (Hong Kong, Taiwan,
and Korea), lifetime prevalence rates of schizophrenia are only 0.12 to 0.41 per 100 persons, whereas rates in Finland, the United States, and Puerto Rico are significantly higher
(1.0 to 2.6 per 100 persons). Whether geographic and cultural variations play a role in the
onset of schizophrenia, culture does seem to matter when it comes to the prognosis for
schizophrenia, and it matters in a surprising way (Kalra, Bhugra, & Shah, 2012). People
with schizophrenia from so-called developing or Third World countries show higher rates
of improvement than people from more developed countries (Hopper, Harrison, Janca,
& Sartorius, 2007). For example, in a cross-national clinical study of people living with
schizophrenia, over a 3-year time period, 84% of those diagnosed with the disorder in
East Asia achieved remission, whereas only 60% achieved remission in northern Europe
(Haro et al., 2011). Whereas many different biopsychosocial reasons have been offered to
explain this puzzling finding (Kalra et al., 2012), two leading factors may be the interrelated arms of treatment and relationships. In many non-Western societies, schizophrenia
may be treated with more informal, community-led methods rather than the medications
described later in the chapter (Hopper et al., 2007). Researchers hypothesize that the
Chapter 4 Schizophrenia Spectrum and Other Psychotic Disorders
145
better outcomes for those with schizophrenia in developing nations are due to relative levels of social connectedness and acceptance in these cultures (Vedantam, 2005), although
further cross-cultural studies are seeking to clarify the findings.
Even if cultural variation in the prevalence of schizophrenia is small, culture might
make a difference in other ways. For one thing, it might affect the form of some hallucinations. For example, visual hallucinations have declined since the 19th century, whereas
auditory hallucinations have increased. The content of hallucinations also tends to reflect themes that are prominent in a person’s culture (Al-Issa, 1977). Among younger
people in Western societies, hallucinations often include technological features—neon
lights explode, loud noises buzz, and computer screens flash. In contrast, the voices of
ghosts, dragons, or animals are likely to appear in the hallucinations of people in cultures
with less modern technology. Furthermore, culture may play a role for individuals who
immigrate to countries where racism and discrimination are present. In a study of secondgeneration Afro-Caribbeans living in the United Kingdom, significantly higher incidence
rates of schizophrenia were evident, suggesting that the stress related to a potentially
hostile social climate may lead to an increase in reported symptoms (Cantor-Graae &
Selten, 2005). In the United States, higher rates of schizophrenia are also seen in migrant
and ethnic minority groups (Kalra et al., 2012). We return to this issue when we discuss
social causes of schizophrenia later in this chapter.
FIGURE 4.1
Hospitalizations for
Schizophrenia in
General Hospitals per
100,000 by Age Group,
Canada, 1999/2000
As this figure shows, younger
males are hospitalized at the
greatest rate across the age
spectrum of schizophrenia.
Source: Based on data from
the Centre for Chronic Disease
Prevention and Control, Health
Canada.
146
Hospitalizations per 100,000
Gender, Morbidity, and Mortality Risk
The morbidity risk for schizophrenia is essentially equal for males and females in Western developed countries (Thara, 2004). However, as Figure 4.1 shows, males tend to
be diagnosed with schizophrenia at earlier ages than females (Rajji, Ismail, & Mulsant,
2009), with the typical age of onset for men being 10–25 years (average of 21), but 25–35
years (average of 27) for women. As a result, males account for the majority of cases of
schizophrenia with onset before age 30; females predominate among cases with later
onset (Hafner et al., 1998). Women also tend to have a bimodal distribution of age at
onset, while men display a unimodal distribution, with a peak for men and women from
age 18–30 years, but a second peak later in life among women (American Psychological
Association, 2013a). The prognosis for men diagnosed with schizophrenia also tends to
be worse (Lang et al., 2013). In comparison to men, women tend to have less-severe
premorbid symptoms, fewer negative symptoms (which is in itself a positive prognostic factor), and lower cognitive impairment. Women with schizophrenia also have lower
rates of suicide than men, even though their reported mood symptoms tend to be worse
(Lester, 2006; Grossman, Harrow, Rosen, Faull, & Strauss, 2008; Koster et al., 2008).
Finally, women have better treatment outcomes. Interestingly, though, gender differences
related to the symptom presentation and age at onset are less evident in people living in
non-Western and developing countries (Venkatesh et al., 2008; Thara, 2004).
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Age Group (Years)
Chapter 4 Schizophrenia Spectrum and Other Psychotic Disorders
Whereas people living with schizophrenia experience a number of symptoms related
to the disorder, they are also at a two-fold greater risk for mortality, compared to sameaged individuals without schizophrenia, with a lifespan shortened by approximately 15–
20 years (Parks, Svendsen, Singer, & Foti, 2006; Auquier, Lancon, Rouillon, & Lader,
2007). This abbreviated lifespan is partially attributable to a higher rate of death by suicide and accidents (Pompili, Lester, Innamorati, Tatarelli, & Girardi, 2008). Within the
population of individuals with schizophrenia, almost one in three people attempts suicide,
and 5–10% die from suicide (Hor & Taylor, 2010; Hunt et al., 2006). In addition, other
medical conditions account for greater than half of the risk for increased mortality, due in
part to an under-recognition and poor treatment of those medical conditions (Szpakowicz
& Herd, 2008). The increased morbidity and mortality associated with schizophrenia substantially increases the disease burden of this mental disorder.
Section Review
Schizophrenia usually follows a course of four stages:
n the premorbid phase,
n the prodromal phase,
n the active phase, and
n the residual phase.
Schizophrenia occurs:
n worldwide at a prevalence rate of about 1%,
n equally in males and females,
n earlier for males than females, and
n usually in the late teens or early 20s, but also as late as the 50s.
Cross-cultural and gender research suggests that:
n the prevalence of schizophrenia is equal across culture, religion, and countries;
n the prognosis is poorer for people living in more developed industrialized nations;
n higher rates of schizophrenia are seen in migrant and ethnic minority groups in
those nations;
n women have a better prognosis than men; and
n morbidity and mortality are high and increase the disease burden of
schizophrenia.
Biological Causes of Schizophrenia
Schizophrenia has always been considered a complex disorder, and most modern researchers agree that it has no single cause. Researchers are studying many potential biological and environmental determinants of the disorder, and some of the factors examined
include heritability, neurodevelopment, fetal and perinatal factors, drug use, trauma, and
socioeconomic status (Brown, 2011). The sections that follow review some of the evidence suggesting that risk for schizophrenia stems from a combination of biological and
environmental factors.
Genetic Vulnerability
Kraepelin’s examination of patients in various countries persuaded him that dementia
praecox was not due to differences in childrearing, food, climate, or the environment.
Because the disorder occurred in widely varying cultures, Kraepelin argued that it must
be a biological disease transmitted genetically. Today, scientists have far better evidence
that genetics play an important role in the development of schizophrenia.
The closer a person’s biological relationship to someone diagnosed with schizophrenia, the greater that person’s risk of developing schizophrenia or one of the schizophrenia
spectrum disorders. The evidence for these conclusions comes from three major lines of
investigation: family aggregation studies, twin studies, and adoption studies. Collectively,
these types of studies have revealed the following:
Chapter 4 Schizophrenia Spectrum and Other Psychotic Disorders
147
n Schizophrenia “runs” or aggregates in families.
n This aggregation is found regardless of the type of research methodology (family,
adoption, or twin studies) used or the country in which the study is performed.
n In many cases, a vulnerability that predisposes a person to schizophrenia
(scientists do not know exactly what) is genetically transmitted.
n Estimates for the heritability of schizophrenia, defined as the observable variance
that is attributable to genetic factors, vary from 60–70% (McGue, Gottesman, &
Rao, 1983; Rao, Morton, Gottesman, & Lew, 1981).
n Genes alone are not sufficient to account for the development of schizophrenia.
Family Aggregation Studies
Family aggregations of schizophrenia have been examined since the early part of the 20th
century. These studies begin with identified people with schizophrenia, called proband
or index cases. The percentage of their family members who are also diagnosed with
schizophrenia is then compared with the percentage diagnosed among family members of
control cases, matched for age and other relevant variables. Family studies tell researchers the extent to which the disorder runs in families, but not why it does so.
Family studies agree on one fundamental point: The closer an individual’s genetic relationship to a person with schizophrenia, the higher the risk of developing schizophrenia.
This relationship is dramatically illustrated in Figure 4.2, which shows data compiled in
a classic paper by Irving Gottesman, a psychologist at the University of Virginia, from
40 of the most reliable family studies conducted between 1920 and 1987 in Germany,
Switzerland, Scandinavia, and the United Kingdom. The progression of increasing risk
for schizophrenia with an increasing degree of family relationship is striking. Equally
striking, however, is the fact that, even at the highest degree of genetic relationship, the
majority of relatives to an index case are not diagnosed with schizophrenia.
Given that the majority of relatives of individuals with schizophrenia are not themselves diagnosed with the disorder, how can researchers evaluate other possible contributors to schizophrenia? As they have for other disorders, twin studies provide one way of
exploring the roles of genetic and environmental factors.
FIGURE 4.2 Family
Risks for Developing
Schizophrenia
The degree of risk for
developing schizophrenia
increases with the extent of
shared genes with a person
who has schizophrenia.
Source: Based on data from
Gottesman (1991).
Percentage Risk of
Developing Schizophrenia
Twin Studies
Because monozygotic (MZ) identical twins are virtual genetic clones of one another, if one
MZ twin has schizophrenia, then the other should as well if schizophrenia were due solely
to genetic transmission. Similarly, because nonidentical or dizygotic (DZ) twins share only
half of their genes, if schizophrenia were due only to genetic factors, and if a DZ twin develops schizophrenia, the co-twin should have a 50% chance of becoming schizophrenic.
To the extent that observed rates of concordance (sharing the disorder) differ from these
anticipated percentages, factors other than genes must contribute to the disorder.
48
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Relationship with Person Who Has Schizophrenia
148
Chapter 4 Schizophrenia Spectrum and Other Psychotic Disorders
As Figure 4.2 indicates, averaged across several studies, the schizophrenia concordance
rate is 48% for MZ twins and 17% for DZ twins (Gottesman, 1991). Another study found
that the concordance rate for one twin having schizophrenia if the other twin has the disorder is 25–50%, compared to about 6–15% for nonidentical twins (Cardno et al., 1999).
Thus, the difference between MZ and DZ rates supports a role for genetic influence, but
the fact that only about half of the identical twins of people with schizophrenia develop
the disorder themselves means that genetics alone cannot account for all of the causality.
Adoption Studies
Another method for evaluating the genetic contribution to schizophrenia examines children born to parents with schizophrenia who are then adopted and raised by families
without schizophrenia in the home. Such adoption studies have usually been conducted
in Europe because of the superior adoption records maintained there. If children born
to parents with schizophrenia but then raised by normal adoptive families later develop
schizophrenia at a higher rate than do adopted children born to parents without schizophrenia, there is support for a genetic contribution to schizophrenia.
The first published adoption study of schizophrenia examined the adult offspring of 47
female patients at the Oregon State Mental Institution (Heston, 1966). These children had
been placed in adoptive families within 3 days of birth. By age 36, 5 of them had been
diagnosed with schizophrenia. In contrast, not one member of a comparison group of 50
adopted children born to mothers without schizophrenia had developed schizophrenia by
age 36. The most comprehensive adoptive studies of schizophrenia were conducted in
Finland and yielded similar results (Tienari, 1991; Tienari et al., 1987, 2004). These studies were able to compare three different groups of children raised by adoptive families:
two groups with biological mothers with schizophrenia and the third group with biological mothers without the disorder. Additionally, the researchers rated the level of discord
or tension in the adoptive home, and categorized the homes as either healthy or disturbed.
Results showed that children of biological mothers with schizophrenia who were raised in
an adoptive family with low levels of discord had only a 1.5% lifetime risk of schizophrenia, higher than the general population (
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