3-18 Schizophrenia

Front 1

Objective

Compare acute and chronic schizophrenia.

Back 1

Schizophrenia is a disorder characterized by deteriorating ability to function in everyday life and by some combination of hallucinations, delusions, thought disorder, movement disorder, and inappropriate emotional expressions. It can be either acute or chronic. An acute condition has a sudden onset and good prospects for recovery. A chronic condition has a gradual onset and a long-term course.

Front 2

Objective

Identify the positive and negative symptoms of schizophrenia.

Back 2

Schizophrenia is characterized by positive symptoms (behaviors that are present that should be absent) and negative symptoms (behaviors that are absent that should be present). Negative symptoms, which include weak social interactions, lack of emotion, and impaired working memory, are usually stable over time and difficult to treat.

Positive symptoms fall into two clusters: psychotic and disorganized. The psychotic cluster consists of delusions (unfounded beliefs, such as the conviction that one is being persecuted or that outer space aliens are trying to control one’s behavior) and hallucinations (abnormal sensory experiences, such as hearing voices when one is alone). The disorganized cluster of positive symptoms consists of inappropriate emotional displays, bizarre behaviors, and thought disorder. The most typical thought disorder of schizophrenia is a difficulty understanding and using abstract concepts.

Front 3

Objective

Cite evidence for and against the notion that schizophrenia is genetic.

Back 3

Monozygotic twins have a much higher concordance for schizophrenia than do dizygotic twin—a finding that has long been taken as strong evidence for a genetic influence. However, there are two limitations:

1. Monozygotic twins have only about a 50% concordance, not 100%. Monozygotic twins could differ because a gene is activated in one individual and suppressed in another or they could differ because of some environmental influence, but regardless of why the differences occur, it is clear that factors other than genetics are at play.

2. There is greater similarity between dizygotic twins than between siblings. Dizygotic twins have the same genetic resemblance as siblings but greater environmental similarity, including that of prenatal and early postnatal life.

Children of a schizophrenic mother have a moderately high probability of developing schizophrenia, even if adopted by non-schizophrenic parents. These results suggest a genetic basis, but they are also consistent with prenatal influence. Consider a pregnant woman with schizophrenia. Many women with schizophrenia have poor nutrition, smoke and drink heavily, and fail to get medical care during pregnancy. If their children develop schizophrenia, we cannot rule out the possibility that these factors have contributed in some way to their disorder.

Front 4

Objective

Cite evidence supporting the neurodevelopmental hypothesis.

Back 4

According to the neurodevelopmental hypothesis, schizophrenia is based on abnormalities in the prenatal (before birth) or neonatal (newborn) development of the nervous system, which lead to subtle abnormalities of brain anatomy and major abnormalities in behavior. The abnormalities could result from genetics, difficulties during pregnancy or birth, or a combination of both. The hypothesis holds that stressful experiences later in life aggravate the symptoms but do not cause schizophrenia. The supporting evidence is that:

1. Several kinds of prenatal or neonatal difficulties are linked to later schizophrenia.
2. People with schizophrenia have minor brain abnormalities that apparently originate early in life.
3. It is plausible that abnormalities of early development could impair behavior in adulthood.

Front 5

Objective

Explain the season-of-birth effect.

Back 5

The season-of-birth effect is the tendency for people born in winter to have a slightly (5% to 8%) greater probability of developing schizophrenia than people born at other times of the year. This tendency is particularly pronounced in latitudes far from the equator. What might account for the season-of-birth effect? One possibility is complications of delivery or early nutrition. Another is viral infection. Influenza and other viral epidemics are most common in the fall. Therefore, the reasoning goes, many pregnant women become infected in the fall with a virus that impairs a crucial stage of brain development in a baby who will be born in the winter.

Front 6

Objective

Discuss the brain abnormalities observed in schizophrenia.

Back 6

In accordance with the neurdevelopmental hypothesis, some (though not all) people with schizophrenia show mild abnormalities of brain anatomy. The abnormalities are small; they vary from person to person; and the results depend on age, symptoms, and so forth. Consequently, although many studies report brain abnormalities in schizophrenia, they disagree about the location of these abnormalities. Here are some possibilities:

1. Studies have shown that the dorsolateral prefrontal cortex shows consistent signs of abnormality. As you might predict, people with schizophrenia perform poorly on working memory tasks.
2. At a microscopic level, the most reliable finding is that cell bodies are smaller than normal, especially in the hippocampus and prefrontal cortex.
3. Lateralization also differs from the normal pattern. In most people, the left hemisphere is slightly larger than the right, especially in the planum temporale of the temporal lobe, but in people with schizophrenia, the right planum temporale is equal or larger. People with schizophrenia have lower than normal overall activity in the left hemisphere and are more likely than other people to be left-handed.
4. Furthermore, the ventricles (fluid-filled spaces within the brain) are larger than normal in people with schizophrenia. The increased size of the ventricles implies less space taken by brain cells.

Front 7

Objective

Identify the drugs commonly used to treat schizophrenia.

Back 7

In the 1950s, psychiatrists discovered chlorpromazine, a drug that relieves the positive symptoms of schizophrenia for most—though not all—patients. Researchers later discovered other antipsychotic drugs in two chemical families: the phenothiazines (which include chlorpromazine) and the butyrophenones (which include haloperidol). Each of these classes of drugs blocks dopamine synapses.

Front 8

Objective

Cite evidence supporting the dopamine hypothesis of schizophrenia.

Back 8

The dopamine hypothesis of schizophrenia holds that schizophrenia results from excess activity at dopamine synapses in certain brain areas. Support for this hypothesis comes from the fact that large, repeated doses of amphetamine, methamphetamine, and cocaine can induce substance-induced psychotic disorder, characterized by hallucinations and delusions (positive symptoms of schizophrenia).

Front 9

Objective

Cite evidence supporting the glutamate hypothesis of schizophrenia.

Back 9

According to the glutamate hypothesis of schizophrenia, the problem relates in part to deficient activity at glutamate synapses, especially in the prefrontal cortex. In many brain areas, dopamine inhibits glutamate release. Therefore, increased dopamine would produce the same effects as decreased glutamate. So the antipsychotic effects of drugs that block dopamine are compatible with ether the excess dopamine hypothesis or the deficient-glutamate hypothesis.

Front 10

schizophrenia

Back 10

Disorder characterized both by a deteriorating ability to function in everyday life and by some combination of hallucinations, delusions, thought disorder, movement disorder, and inappropriate emotional expressions

Front 11

positive symptom

Back 11

Presence of a behavior not seen in normal people

Front 12

negative symptom

Back 12

Absence of a behavior ordinarily seen in normal people, for example, lack of emotional expression

Front 13

delusion

Back 13

Beliefs that other people regard as unfounded, such as the belief that tone is being severely persecuted

Front 14

hallucination

Back 14

Sensory experience that does not correspond to reality

Front 15

thought disorder

Back 15

Disorder of schizophrenia indicted by impaired thinking, such as difficulty in understanding and using abstract concepts

Front 16

differential diagnosis

Back 16

Identification of a condition as distinct from all similar conditions

Front 17

Chlorpromazine (Thorazine)

Back 17

The first drugs found to relieve the positive symptoms of schizophrenia

Front 18

antipsychotic (neuroleptic) drugs

Back 18

Drug that relieves schizophrenia

Front 19

phenothiazines

Back 19

Class of antipsychotic drugs that includes chlorpromazine

Front 20

butyrophenones

Back 20

Class of antipsychotic drugs that includes haloperidol