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Psychopathology
Psychopathology is the study of diseases of the mind. Defining what constitutes
evidence that a person has mental illness is tricky business. Here I shall use the criteria
that have been published by the American Psychiatric Association in the Diagnostic and
Statistical Manual of Mental Disorders, 4th edition (DSM-IV):
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The individual must present a set of interrelated symptoms which involve
distress and significant impairment of function (typically with work or social
life),
The source of the distress must be within the person, not just in the
environment. Put another way, if the individual is in an environment that is so
bad that we would expect any person in it to be so distressed, then a diagnosis of
mental illness is not warranted.
The abnormal behavior leading to a diagnosis of mental illness must be
involuntary.
Diagnosis. The DSM-IV presents, for each disorder, a set of objective criteria
that must be met before the diagnosis is made. These criteria are based on
characteristics that should be easy to observe directly (including the patient’s selfreports of distress), so it should be unlikely that two different diagnosticians would made
different diagnoses when presented with the same case. In fact, the DSM-IV is said to
be very reliable.
Prevalence. You may be surprised at how common mental illness is, and at how
large the sex differences are for some disorders -- see Gray’s Figure 16.1 below:
Gray-16.doc
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What Causes Mental Illness?
Brain Disorders. From this perspective, mental illness is caused by brain
dysfunction. The brain dysfunction may have been inherited or may have resulted from
accidents, exposure to toxins (including drugs and alcohol), or infections.
Psychodynamics. Here the illness is thought to result from abnormal mental
forces, such as repressed sexual or aggressive desires (Freud). Those who adopt this
perspective usually argue that the mental abnormality is caused by the individual not
having been able to resolve mental conflicts that are common early in life (such as
young boys’ desire to have sex with mothers and kill their fathers).
Learning. From this perspective, the thoughts and behaviors that accompany
mental illness stem are learned -- that is, they result from having experiences that
reinforce maladaptive behaviors and cognitions.
Culture. A particular culture may provide an environment that makes certain
mental illnesses much more likely than they are in most other cultures. As an example,
Gray notes that eating disorders started becoming quite frequent in Western culture in
60’s and 70’s, when cultural forces convinced young women in the middle and upper
classes that the ideal body shape was that of Twiggy (5 foot 7, 92 lb). Apparently many
women believe that men prefer such a body shape, and feel that they must achieve it to
be attractive. On the other hand, if you ask men what shape they really want, most will
choose that of Marilyn Monroe over Twiggy.
Predisposing, Precipitating, and Maintaining Causes. An individual may
have a genetic constitution or learned beliefs and habits that make em more
susceptible to mental illness. Such predisposing causes may never lead to mental
illness, unless a precipitating stressful event occurs, such as a loss (of job, marriage,
loved one, health) or most any major change in life. Maintaining causes are those
factors which act to keep a person ill once mental illness has started. For example, the
disturbed person may be rewarded by getting attention. Less pleasantly, the disturbed
person may neglect him- or her-self (not eating properly, not sleeping properly, and so
on) and engage in other behaviors (such as withdrawing from family, friends, and other
social support) that make recovery unlikely.
What Causes Sex Differences in Rates of Mental Illness? As shown in Figure
16.1, women are much more likely than men to be diagnosed with anxiety disorders and
mood disorders, and men are more likely to be diagnosed with substance abuse
problems and antisocial personality. Why is this so? Some of the difference may be
biological, a result of sex differences in brain structure and hormones, but other
explanations come to mind.
Perhaps men are less likely to be diagnosed with anxiety and mood disorders
because they think that admitting to them is a sign of weakness, so they do not seek
professional treatment. They may treat themselves instead, with alcohol and other
drugs and then act out aggressively, resulting in diagnoses of substance abuse and
antisocial personality.
It is also possible that women are simply more likely than men to be subjected to
the sorts of stressors that produce anxiety and mood disorders. They have been,
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after all, more likely than men to live in poverty, to experience discrimination in the
workplace, to have been abused in childhood and adulthood, and to fill a position
(Hausfrau) where they are isolated from other adults and held responsible for events
over which they have little control.
Another possibility is that the sex differences seen in Figure 16.1 are, at least in
part, a result of stereotyping on the part of diagnosticians. If they think that some
mental illnesses are more likely in women than in men, then they will be more likely to
think of and make those diagnoses in women than in men. Thomas Widiger was one
of my classmates at Miami University, from which we both received our doctoral
degrees. Thomas and his colleague, Maureen Ford, have conducted research into the
topic of sex bias in diagnosis.
These researchers sent fictitious case histories to hundreds of clinical
psychologists and asked them to make a diagnosis using the DSM. One of the case
histories was written to include information that was consistent with the criteria for a
diagnosis of antisocial personality, a disorder in which the individual has no sense of
guilt and no respect for others’ rights. The other case history included information
consistent with a diagnosis of histrionic personality, a disorder in which the individual
is considered to be overly emotional, seeking attention by dramatic behavior. In half of
the cases the patient was described as a man, in half as a women. Sex bias was very
evident in the diagnoses made. Whether the case details were more consistent with a
diagnosis of antisocial personality or histrionic personality, the diagnosis of antisocial
personality was more likely if the patient was said to me male rather than female and
the diagnosis of histrionic personality was more likely if the patient was said to be
female rather than male.
Medical Student Syndrome. When medical students learn the symptoms of a
disease, they often find that some of the symptoms sound like characteristics of
themselves, and then they start to wonder if they have that disease themselves. A
similar phenomenon occurs if you go to the library, get the PDR, and read all of the
possible side effects of that new prescription drug that you are taking -- you start feeling
like you have many of those rare side effects. In the same way, psychology students
reading about the symptoms of mental illnesses, often identify with some of the
symptoms (as will most persons) and start to suspect that they have this or that mental
illness. Beware this.
Anxiety Disorders
Anxiety and fear can be quite adaptive in terms of preparing a human for
vigorous physical activity when encountering a threatening event and in terms of making
more likely behaviors that assure our survival. Consider, for example, an ancestor of
yours who is exploring a novel place. There may be dangers in this new place, our
ancestor could get in trouble if he were not very vigilant and prepared to take action to
deal with any threat that might suddenly arise. His sympathetic nervous system is
aroused, preparing him for such action, and he becomes hypervigilant, constantly
scanning the environment for signs of danger. Phenomenologically he feels on edge,
he is worried. This is anxiety. When he sees an angry bear running towards him, his
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anxiety changes to fear. Hopefully the changes accomplished by earlier arousal of his
sympathetic nervous system have prepared him well to deal with this threat.
Cleary the ancestral human who had no capacity for anxiety and fear would be at
a disadvantage. Our inherited capacity for anxiety and fear can, however, cause us
problems in the modern world, where our environment seems to be in a constant state
of rapid change and where we are continually bombarded by news about threats not
only from our immediate environment but from places far removed from us. In this
modern world, the mechanisms of anxiety and fear that served our ancestors so well
may become maladaptive. Levels of generalized anxiety have increased dramatically
during the last 50 years in our modern world.
Generalized Anxiety Disorder
Generalized anxiety disorder is characterized by being in an almost constant
state of worry. The anxiety is not focused on a single thing, but rather on multiple
things. Common symptoms include muscle tension, sleep disturbances, gastrointestinal
problems, hypervigilance, over-reactivity to environmental stimuli (such as unanticipated
sounds), and other symptoms of heightened activity of the sympathetic nervous system.
Approximately 5% of North Americans have, at sometime during their lives,
generalized anxiety disorder so serious that they meet the rather stringent diagnostic
criteria of the DSM. Considerably more than 5% have trouble with generalized anxiety
that is just not quite as long lasting or as disruptive as necessary to meet the DSM
criteria.
Heritability. The genes that make one susceptible to developing a generalized
anxiety disorder appear to be the same genes that make one susceptible to major
depression. A family history of either generalized anxiety disorder or major depression
predisposes one to develop either generalized anxiety disorder or major depression.
Individuals who have had generalized anxiety disorder are more likely than others to
develop major depression later in life and those who have experienced major
depression are more likely than others to develop generalized anxiety disorder later in
life.
Environmental Factors. Having experienced frequent and unpredictable
traumatic experiences during childhood may predispose one towards developing
generalized anxiety disorder later in life. The disorder typically first appears in
adulthood following some major life change, such as leaving home and going to college,
getting a new job, having a baby, suffering a life-changing accident or illness, etc.
Phobias
A phobia is an intense and irrational fear of an object or event. The person
typically knows that the fear is irrational, but cannot control it. Specific phobias most
often involve things that were reasonably associated with danger for our ancestors,
such as snakes, spiders, lightening, high places, and darkness. We have inherited
the genes that predispose us to learn to fear these things, even though there are more
commonly encountered dangerous things in our modern world that we don’t so easily
learn to fear, such as electrical outlets. Specific phobias are diagnosed much more
often in women than in men. Men may be less likely to admit to such phobias or may
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be more likely to learn to overcome them -- from early childhood on boys and men are
taught that it is not appropriate to show fear.
Social phobia involves a fear of being evaluated by other people.
Obsessive-Compulsive Disorder
Obsessions are disturbing thoughts that continually pester one, much like the
tune you hear this morning and now you can’t get it out of your head. Most of us have
experienced such obsessions now and then (especially during childhood), but they don’t
become so frequent that they seriously disrupt our lives. For example, while on your
way to school, you keep thinking, “did I lock the door to my house -- I remember doing
it, but might my memory be false -- might I just be assuming that I locked the door
because I always lock my door when I leave -- now that I think of it more carefully, I
don’t clearly remember locking it today -- that memory I have could be of having locked
it yesterday -- and so on.” Obsessions usually involve some threat to oneself or to
loved ones.
Compulsions are repetitive actions that are usually performed in response to
an obsession. Performing them may, temporarily, provide relief from the obsession.
Common compulsions include checking and cleaning. Consider the person who spends
hours every day checking and re-checking doors to be sure they are locked,
appliances to be sure they are turned off, water faucets to be sure they are not running,
and so on. Also consider the person who spends hours every day washing her hands,
over and over again. These actions, performed a reasonable number of times, are quite
appropriate -- it is when they must be repeated over and over again without necessity
that they become compulsions.
Brain scans done on obsessive-compulsive persons show abnormally high
levels of activity in the caudate nucleus, part of the basal ganglia known to be
involved in the initiation of learned behaviors. Following successful treatment,
activity in the caudate nucleus declines.
Panic Disorder
With panic disorder a sense of absolute terror springs up unpredictably,
without any apparent environmental trigger. Since it cannot be prevented by
avoiding specific environmental events, those who suffer panic disorders may live in
near constant fear of the next one. This fear may lead to the development of
agoraphobia, fear of and avoidance of public places -- after all, who wants to be the
focus of attention by having a panic attack?
A panic attack is accompanied by high arousal, including tachycardia (rapid
heart rate) and respiratory difficulty. Having experienced tachycardia produced as a
side effect of a blood pressure medication, I can assure you that the feeling is scary,
even though not otherwise dangerous.
Experimental manipulations, such as inhalation of carbon dioxide, that
produce increases in heart and breathing rates can trigger a panic attack in susceptible
individuals. This suggests that such persons are unusually likely to interpret even
modest increases in heart and breathing rates as dangerous, with fear of that
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danger then leading to even greater activation of the sympathetic nervous system,
including even greater increases in heart and breathing rates, in a vicious cycle.
One treatment for this disorder is a cognitive therapy which teaches patients to
consider physiological arousal as a temporary state which should not be feared.
Posttraumatic Stress Disorder
This disorder follows, either immediately or as long as months later, a
traumatic experience such as being tortured, violently assaulted, or continually exposed
to the horrors of war. Memories of the traumatic event plague the victim both night
and day. Common symptoms include sleep disturbances, sympathetic arousal,
irritability, depression, and feelings of guilt (especially when others did not survive the
same traumatic event).
Disorders of Mood
It is perfectly normal sometimes to feel low -- that is, sad, blue, and disinclined to
action. It is also perfectly normal sometimes to feel high -- that is, unusually aroused
and energetic. When these moods are extreme, long lasting, and/or very frequent, one
can suffer impairment of normal functioning and can become a danger to himself or to
others.
Depression
As noted earlier, there are similarities between depression and anxiety. Both
anxious and depressed persons think of bad things. The anxious person worries
about bad things that might happen. The depressed person thinks about all the bad
things that have happened and concludes that life is miserable, that he is worthless,
and that there is no sense in trying any more. Depressed persons often report that they
no longer experience pleasure doing the things that used to give them pleasure,
including things as basic as eating and having sex. In some cases appetite may be
increased -- as if eating were the only thing left that the person was any good at and
which would give him any pleasure. Depressed individuals may experience agitation
(such as pacing) or retardation of motor function (such as slowed speech).
Major Depression will be diagnosed when the symptoms are severe and have
persisted for at least two weeks. Dysthymia will be diagnosed when the symptoms are
less severe and have been present for at least two years. Double Depression is
diagnosed when a patient is usually dysthymic but also has bouts of major depression.
The Brain and Depression. Drugs which enhance the action of monoamine
neurotransmitters (dopamine, norepinephrine, and serotonin) can be effective in
treating depression and anxiety disorders, and drugs that decrease the action of
monoamine transmitters can produce depressive mood in some (not all) persons.
Accordingly, it is tempting to conclude that depression and anxiety disorders are caused
by abnormalities in brain circuits where the monoamines are the neurotransmitters.
There are, however, several observations that seem to be inconsistent with that
hypothesis:
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 Drugs that almost immediately enhance the action of monoamine
neurotransmitters do not immediately relieve depression or anxiety. It takes
about two weeks for them to have an effect.
 During those two weeks the brain makes a number of changes in response to the
drug, and it may be these brain changes that account for the therapeutic value of the
drug.
 Among those changes are some processes that oppose the action of the drug,
so that after two weeks the drug may no longer be enhancing the action of
monoamine neurotransmitters.
 Drugs that enhance the action of serotonin alone or of norepinephrine alone
can be equally effective in the same individuals, despite the fact that serotonin and
norepinephrine are involved in different brain areas with different functions.
Environmental Factors. Persons who have recently suffered a stressful life
event, such as loosing one’s job, are more likely to experience depression than are
persons who have not recently experienced such an event. This may result, in part,
from the following confounding factors:
 People who are predisposed towards depressive illness may be more likely to
engage in behaviors that lead to stressful life events (but depression is also more
likely following losses for which the person cannot reasonably be blamed, losses such
as the death of a loved one), and
 Depression may cause persons to think about recent bad things more than
they would normally would have and may cause them to exaggerate how bad those
things are.
Hopelessness Theory. Martin Seligman and others have proposed that
depression results when persons attribute negative events to factors that are stable
(not likely to change) and global (affecting all of one’s life) rather than to factors that are
unstable (likely to change) and specific (affecting only one or a few parts of one’s life).
Suppose you failed your first exam in all of your courses this semester. If you were
to interpret this as indicating that you are an absolutely worthless moron (a stable
and global cause of your failure), then you are predisposed to depression. On the other
hand, if you interpret this as indicating that you did not study hard enough (something
you can change) or if you decide that you are just not good at scholarly exercises but
that you are good at lots of other things (a specific rather than a global attribution), then
you are unlikely to get seriously depressed over it.
Seligman and his colleagues developed an attributional-style questionnaire
that measures the extent to which one makes stable and global attributions about
positive and about negative characteristics. Persons whose test results indicate that
they attribute negative events to stable and global failings of themselves are, in fact,
more likely to suffer depression.
Bipolar (Manic-Depressive) Disorder
Here the individual shifts between periods of depression and mania, with or
without a period of normal mood between depressive and manic phases. Each phase
may last as long as several months or as short as a few days.
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During the manic phase the person with bipolar disorder is on a high, often a
euphoric high with abundant energy and feelings of great confidence and power.
Feeling like superman can lead to dangerous behaviors, such as jumping off of tall
buildings and then discovering that you cannot fly after all. Some persons experience
the manic phase as unpleasant -- a period of high irritation, suspiciousness, and/or
rage.
Lithium is effective in treating bipolar disorder, but the mechanism of its action is
unknown.
Cyclothymia
This disorder is like bipolar disorder, except the mood swings are not as great.
The high side of the mood is called hypomania. The great energy and confidence
present during hypomania can contribute to productivity. For example, cyclothymia
is relatively frequent among highly creative writers and artists and among those
individuals their best works are typically created during periods of hypomania.
Hypomania can also contribute to behaviors the person later regrets, such as
shopping sprees and sexual extravagances.
Health Psychology
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One’s mental state can influence one’s health in a variety of ways, including:
Emotional distress can be expressed as bodily symptoms in the absence of any
physical disease.
Negative emotions can contribute to physical disease.
People can learn to engage in behaviors that are good for their health or in
behaviors that are bad for their health.
Somatoform Disorders (once called psychosomatic disorders) are those in
which the symptoms are bodily but there is no physical explanation for the symptoms -the causes are thought to be psychological -- you know, “its all in your mind.” Included
in the somatoform disorders are conversion disorder and somatization disorder.
In conversion disorder one loses some bodily function but there is no physical
explanation for the loss. Examples include loss of sight, loss of hearing, loss of skin
sensation over part of the body (such as glove anesthesia), and partial paralysis (such
as paralysis of the trigger finger in a soldier). While conversion disorder is still seen in
many parts of the world, it has become very rare in North America and Western Europe.
This may result from changes in Western culture legitimizing the psychological
expression of emotional distress and making incredible the loss of bodily function in the
absence of a physical explanation.
In somatization disorder (hypochondriasis) the patient has a long history of
allegations of assorted medical problems, usually involving symptoms that are vague
and/or fit into no pattern of a known medical syndrome, and no underlying physical
explanation of the symptoms can be found.
Persons who are in good health at the time of a great personal loss (like the
death of a loved one) are more likely to become physically ill after the loss. This may
be in part due to their failing to take care of themselves after the loss (not eating well,
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not sleeping well, self-medicating with alcohol, and so on), but it may also be due to the
direct effects of grief upon bodily functioning, including immune system function.
There is good evidence that emotional distress can weaken the immune
system. Our stress reaction evolved during a time when stressors were dangers
which could be dealt with by vigorous physical action (flight or fight). Preparing us for
such vigorous physical action, our stress reaction diverts to the muscles all bodily
energies serving other functions that are not absolutely vital. One such function is
immune response -- if a large predator is about to attack and eat you, you need all the
muscle energy you can get, and it would not hurt to divert energy from the immune
system to the muscles for a short time. In the modern world, however, our stressors
are not often the sort which can effectively be dealt with by vigorous physical exertion
and they are often present for long periods of time, long enough for us to get infections.
Personality and Health. The best known example of a relationship between
personality and health is that of the so-called “Type A” personality. A person with
such a personality puts himself under chronic time pressure, is highly competitive,
impatient, and easily angered. Such persons are more likely to develop
cardiovascular illness than are persons with more laid-back (Type B) personalities. It
appears that the irritability and hostility are the critical variables causing Type A
persons to be more likely to suffer from cardiovascular disease. A history of anxiety
and/or depressive illness is also associated with cardiovascular disease.
Psychoactive Substance Abuse Disorders
Here we are dealing with problems associated with the use of drugs which affect
the brain and produce changes in emotions, perceptions, and/or thoughts.
Drug Abuse is indicated when the individual frequently uses drugs in a way that
is harmful to the self or society.
Drug Dependence (addiction) is indicated when the person feels compelled to
take the drug and feels very distressed if he does not take it.
Gray focuses on the most abused drug in our culture, alcohol. He references
the work of Steele and Josephs (which we discussed earlier) on interpreting the effects
of alcohol intoxication in terms of cognitive myopia.
“Withdrawal” refers to ill effects that follow cessation of drug taking after having
taken the drug for a considerable time. About 8 to 20 hours after stopping alcohol
consumption, an alcohol addict shows a number of symptoms caused by great overactivity of the brain. Referred to as the DTs (delirium tremens), these symptoms include
muscle tremors, sweating, tachycardia, panic, hallucinations, and even brain seizures.
Without medical attention, the DTs can be fatal in 15 to 50% of cases.
Long-term abuse of alcohol can damage the brain, the liver, and other organs.
Damage to the brain can cause Korsakoff’s syndrome, in which there is severe
impairment of memory and problems with motor coordination. When pregnant women
abuse alcohol, the baby can develop fetal alcohol syndrome, which includes both
physical deformities and mental retardation.
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As noted earlier in the course, susceptibility to becoming addicted to alcohol is
heritable, as may be susceptibility to becoming addicted to other drugs of abuse.
Dissociative Disorders
“Dissociate” means to disconnect. In a dissociative disorder one part of a
person’s life is disconnected from another part of e’s life. In dissociative amnesia
the person loses memory for part of e’s life -- it may be a small part or a very large part
(such as everything prior to the start of the disorder). In dissociative fugue the person
not only loses memory of e’s previous life but also leaves home and starts a new
identity elsewhere. After days or months the person resumes e’s previous identity,
remembers what e had forgotten, and forgets what took place during the period of the
fugue.
Gray focuses on dissociative identity disorder, previously known as multiple
personality disorder. This disorder is characterized by the individual assuming two or
more (there may be dozens) different identities/personalities. At certain times, usually
in response to some provocation, the person will switch from one identity to another.
The differences in the personalities may be great, but usually they are not.
Most persons diagnosed with dissociative identity disorder are women who
report having been abused as children. Apparently these abused children learn to
deal with the abuse by creating a second personality, one who is better able to deal with
the abuse than they are themselves. After learning how to deal with the abuse by
creating a second personality, these persons may start to use the second personality to
deal with other problems and may even create additional personalities to deal with other
problems. It should be noted that dissociative personality disorder is quite rare, even
among women who were abused as children, so there must be important
predisposing factors (such as an exceptional ability to fantasize) that determine which
abused girls will developed dissociative personality disorder and which will not.
The frequency of reported cases of dissociative identity disorder was very low
prior to the 1970’s. Following the publication of a popular book and the release of a
movie about a woman (Sybil) with dissociative identity disorder, the frequency of the
disorder increased greatly (but it is still rare). Most of the persons diagnosed with this
disorder in recent years did not even realize that they had the disorder when they
started therapy, and neither did their friends or family. Furthermore, the differences in
the personalities are very small, even subtle. Their disorder was “discovered”
during therapy, often with the help of hypnosis. Skeptics note that some of the
“memories” uncovered during this therapy have been hard to believe -- for example,
stories about having been tortured by satanic cults. All of this has led to the suggestion
that the disorder in many of these case is “iatrogenic” -- that is, “created by the
therapy.”
Schizophrenia
Schizophrenia is both a very disabling illness and relatively frequent.
Approximately 1 in 100 persons will have schizophrenia at some time in their lives.
Symptoms most often first appear in men between 18 and 25 and in women between
26 and 45.
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“Schizophrenia” means “split mind.” This is not a dissociative identity problem,
but rather a splitting apart of basic mental processes such as attention, emotion,
motivation, perception, and thought. When these mental processes are isolated from
one another, the result is unusual and disorganized thoughts and behaviors. This
results in the person’s mind being split from reality as the rest of us know it.
The symptoms found in persons with schizophrenia are remarkably variable
between individuals and across time. The DSM specifies the following criteria for a
diagnosis of schizophrenia:
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a long-term and serious decline in the ability to function normally with respect to
taking care of oneself, social relationships, and work, and
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at least 2 of the following 5 types of symptoms:
1. Delusions -- false beliefs, commonly including delusions of persecution,
delusions of grandeur, and delusions of being controlled by mysterious entities
or forces.
2. Hallucinations -- sensory perceptions in the absence of appropriate stimulation.
These are usually auditory, most often voices. The voices come from within.
Interestingly, the voices can be quieted if the person immobilizes his own vocal
apparatus by humming, counting aloud, or similar actions.
3. Disorganized Speech, which is assumed to reflect disorganized patterns of
thought. One type is overinclusion, in which simple word associations rather
than logic guides the flow of speech. For example, “For dinner we had veal
cutlets, tossed salad, and French fries, with lots of German, Polish, Spanish, and
the United Snakes.” Another type is paralogic, where faulty deductive reasoning
is apparent. For example, “President Bush is a Texan. I come from Houston,
which is in Texas, so I am a President too.”
4. Disorganized Behavior -- inappropriate or ineffective behaviors. Gray’s
examples include a person wearing winter clothing on a hot day [but see Adaptive
Value of Religious Ritual] and being unable to prepare a simple meal. Included in
this category are catatonic behaviors, behaviors in which the person is
unresponsive to the environment. In catatonic stupor the individual shows a
complete lack of movement and may stay in an unusual position for long periods
of time.
5. Negative Symptoms -- here we see a lack of, or reduction in, the sorts of
behaviors, thoughts, emotions, and drives that are typical of normal people.
Bodily movements may be slowed, speech slowed, basic drives such as hunger
lacking, and emotion flat.
There have been attempts to categorize schizophrenia into a subcategories on
the basis the type of symptoms expressed, but this attempt has not been very fruitful.
As noted earlier, the symptoms are remarkably variable among individuals and across
time.
Causes of Schizophrenia
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Genetics. The evidence for heritability of schizophrenia is quite strong. The
basic research technique here is to identify individuals who have schizophrenia (the
index cases) and then see which of their relatives also have schizophrenia. If a
particular relative also has schizophrenia, then the index case and the relative are said
to be concordant. Concordance is positively related to degree of biological
relationship, as shown in Gray’s Figure 16.3 below:
Also, when we look at both the biological and the adoptive relatives of persons
with schizophrenia, we find much higher concordance with biological relatives than with
adoptive relatives.
Birth Defects. Difficult births, in which there is brain trauma, can lead to
schizophrenia, as can a poor prenatal environment. When pregnant mothers have
poor nutrition, there babies are more likely to become schizophrenic. Those born in
late winter or early spring (when viral infections are more common) are also more
likely to become schizophrenic.
Predicting Schizophrenia. If the primary causes of schizophrenia are things
that happen very early in life (like the genes one gets and prenatal, birth, and other early
experiences), then we should be able to predict, from the behavior of children, who will
and who will not develop schizophrenia. There have been established significant
correlations between childhood deficits in attention, verbal memory, and motor
skills that and the onset of schizophrenia in adulthood, but there correlations are not
large enough in magnitude to be of practical use in predicting who will become
schizophrenic.
Brain Structure. There have been demonstrated subtle but reliable
differences in the structures of the brains of persons who develop schizophrenia and
the brains of those who do not. The evidence indicates that these differences exist
long before the onset of the illness, perhaps even at or before birth.
Dopamine. Drugs which block the release of dopamine are effective for
reducing the hallucinations and delusions that so commonly accompany
schizophrenia. Drugs like amphetamine and cocaine, which increase the action of
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dopamine, make worse the hallucinations and delusions and can even produce these
symptoms in persons who are not schizophrenic.
These observations would seem to indicate that schizophrenia is caused by
having too much activity in neural circuits where dopamine is the neurotransmitter.
There are, however, a few problems with this hypothesis: Drugs that block the
release of dopamine do not help much with the other symptoms of schizophrenia
(disorganized speech and behavior and the negative symptoms) and drugs that
increase the action of dopamine do not aggravate those symptoms.
It may be that schizophrenia is caused by having too much activity in some
neural circuits that involve dopamine but too little activity in other neural circuits that
involve dopamine -- or there may be some entirely different brain dynamic that has not
yet been found.
Family. Finnish researchers studied two groups of adopted children. One
group was at high genetic risk because their biological mothers had schizophrenia. The
other group was at low risk because neither of their biological parents was known to
have schizophrenia. The research indicated that when the adoptive parents interacted
with the high risk children in an especially disorganized and hyperemotional way,
then those children developed disorganized thought patterns like those of
schizophrenics. This same parental behavior was not, however, associated with such
an effect on the children who had low genetic risk for schizophrenia.
The results of this research strongly suggest that the development of
schizophrenia requires both a genetic predisposition and an environmental trigger, but
there remains an alternative explanation. Remember that parental behavior can be a
result of rather than a cause of children’s behavior. Perhaps the observed correlation
between parental behavior and children’s thought patterns was a case of the children’s
characteristics causing differences in the parents’ behavior.
Cultural Differences. Although many of the characteristics of schizophrenia are
pretty much the same in all cultures, there are some striking differences in recovery
statistics. The odds of recovery from schizophrenia within two years are almost three
times higher in less developed countries compared to in the industrialized world. So
why is recovery so much more likely in less developed countries. Some have
suggested that the antipsychotic drugs used in indistrialized countries reduce
symptoms but also prolong the illness. Persons with schizophrenia in a less developed
country may also have a much better support system (living with many relatives), be
less likely to be stigmatized as mentally ill, and be more likely to be able to continue
to contribute to society despite their schizophrenia -- a person with schizophrenia who
could not hold down a job in a factory or office might well be able to do just fine on a
third-world farm.
Revised March, 2006. Illustrations now have alternative text.
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