Ch.17 Schizophrenia and the Affective Disorders
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Copyright 2001 by Allyn & Bacon
Carlson (7e) PowerPoint Lecture Outline
Chapter 17: Schizophrenia and the Affective Disorders
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Copyright 2001 by Allyn & Bacon
Schizophrenia
■ Schizophrenia represents a disorder of thought and emotion, but not a “split-personality”● Thought disorder● Hallucinations● Delusions● Bizarre behaviors
■ The incidence of schizophrenia is about 1%● No gender differences in incidence
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Copyright 2001 by Allyn & Bacon
Symptoms of Schizophrenia
■ Positive symptoms include delusions, hallucinations and thought disorder● Delusions are beliefs that are contrary to reality
◆ Delusions can involve control, grandeur, or persecution
● Hallucinations are perceptions that occur in the absence of stimuli (often auditory and/or olfactory)
● Thought disorder: disorganized and irrational
■ Negative symptoms involve a loss of normal behaviors, such as● Poverty of speech and low initiative● Social withdrawal and diminished affect
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Copyright 2001 by Allyn & Bacon
Heritability of Schizophrenia
■ The heritability of schizophrenia is a strong indicator of a biological basis for schizophrenia● Adoption studies
◆ Adult schizophrenics that were adopted as children are likely to have schizophrenic biological relatives.
● Twin studies◆ Concordance rates for schizophrenia are higher for
identical than for fraternal twins: ● No single gene has been identified for schizophrenia
◆ Genes may pass on a susceptibility to develop schizophrenia
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Copyright 2001 by Allyn & Bacon
The Dopamine Hypothesis of Schizophrenia
■ The “dopamine hypothesis” is that the positive symptoms of schizophrenia involve overactivity of brain dopaminergic synapses● Chlorpromazine (CPZ) was identified as an effective
antipsychotic (AP) agent◆ CPZ was later found to block DA receptors (D2 receptors)◆ Other drugs that block DA receptors also reverse
schizophrenia
● Stimulants such as amphetamine that release DA can produce the positive symptoms of schizophrenia
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Copyright 2001 by Allyn & Bacon
DA Activity in Schizophrenia
■ PET studies indicate greater release of dopamine in the striatum of schizophrenics to a test dose of amphetamine● Amount of dopamine released was related to the increase in
positive schizophrenia symptoms■ Studies of dopamine receptors in schizophrenic brain
have provided mixed results● Postmortem studies suggest increased numbers of D2 receptors
in striatum (but may be due to exposure to AP drugs)◆ The striatum is a motor control region: may be the wrong site◆ Schizophrenia may be related to D4 or D3 receptors
● Clozapine is an effective AP drug that does not interact with D2
◆ Clozapine acts on D4 receptors in the accumbens
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Copyright 2001 by Allyn & Bacon
Antipsychotic Medications
■ Antipsychotic medications diminish the thought disorder evident in schizophrenia
■ Side effects of antipsychotic medications include● Autonomic problems (dry mouth)● Skin-eye pigmentation● Breast development (increased prolactin release after
blockade of dopamine neurons)● Tardive dyskinesia: facial tics and gestures
◆ TD is due to overstimulation of DA receptors
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Copyright 2001 by Allyn & Bacon
Brain Damage and Schizophrenia
■ The negative symptoms of schizophrenia are related to brain damage● The neurological signs evident in schizophrenia include
◆ Eye tracking problems◆ Catatonia◆ Problems with blinking, eye focusing, and visual pursuit
● Schizophrenics exhibit enlarged brain ventricles, which suggests loss of brain cells
● Regions of schizophrenic brain that are abnormal include◆ Prefrontal cortex◆ Medial temporal lobes ◆ Medial diencephalon
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Copyright 2001 by Allyn & Bacon
Ventricular Enlargement in Schizophrenia
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Normal Twin Schizophrenic Twin
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Causes of Brain Damage in Schizophrenia
■ The neurological symptoms of schizophrenia may be caused by● Birth trauma (obstetrical issues)● Viral infections that impair neural development during the
second trimester◆ Seasonality effects (schizophrenia is more likely for winter births)
● Nutritional issues (Hunger Winter: female offspring were more likely to exhibit schizophrenia than male offspring)
● Maternal stress may compromise the immune system of the mother and lead to a greater chance of contracting a viral infection
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Copyright 2001 by Allyn & Bacon
Seasonality and Schizophrenia
■ Children born during the late winter and early spring are more likely to develop schizophrenia● Seasonality effect occurs in
cities but not the countryside■ Seasonality effect may be
related to the mother contracting a viral infection during the second trimester of fetal development
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Copyright 2001 by Allyn & Bacon
Hypofrontality and Schizophrenia
■ Hypofrontality refers to the decreased activity of the dorsolateral prefrontal cortex● Damage to the prefrontal cortex impairs behavioral flexibility
(card sorting task)● Schizophrenics show decreased activity in the prefrontal cortex
■ Abuse of PCP produces positive and negative symptoms of schizophrenia● Positive: related to indirect actions of PCP on accumbens DA● Negative: related to decreased DA utilization in prefrontal
cortex following PCP treatment
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Copyright 2001 by Allyn & Bacon
Major Affective Disorders
■ Affect refers to emotions, moods, and feelings● Our affect is usually a reflection of our experiences● In the major affective disorders, our emotional
reactions are at the extremes and may not be related to our actual experiences
■ The major affective disorders include● Bipolar disorder - alternating cycles of
◆ Mania: euphoria, delusions◆ Depression: profound sadness, guilt, suicide risk
● Unipolar depression: continuous, episodic
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Copyright 2001 by Allyn & Bacon
Biological Bases of Affective Disorder
■ Heritability of affective disorder (AD) has been established in twin studies and family studies● Bipolar disorder may be related to a single gene
■ Depression is amenable to physical treatments including● Pharmacological treatments
◆ MAO inhibitors (e.g. iproniazid)◆ Serotonin reuptake inhibitors (e.g. Prozac)
● Electroconvulsive shock therapy (ECS)● Sleep deprivation
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Copyright 2001 by Allyn & Bacon
Monoamine Hypothesis of Depression
■ Depression results from reduced activity of brain monoamines● Reserpine depletes monoamines--> depression● Suicidal depression is related to a low level of 5-
HIAA● Antidepressant meds increase either NE or 5-HT
◆ Usually via blockade of monoamine reuptake● Tryptophan deletion procedure:
◆ Reduces brain 5-HT levels◆ Reinstates depression in former depressed patients
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Copyright 2001 by Allyn & Bacon
REM Sleep and Depression
■ Sleep pattern is disrupted in depressed persons● Reduced REM latency, reduced stages 3 and 4 sleep
■ REM deprivation improves mood■ Antidepressant drugs suppress REM sleep, and
increase slow-wave sleep■ Persons who have short REM sleep latency are
more likely to develop depression■ REM sleep deprivation is more effective than is
total sleep deprivation (effects last longer)
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Copyright 2001 by Allyn & Bacon
Seasonal Affective Disorder
■ SAD is a form of depression evident in winter months (short days/long nights)
■ SAD involves● Mood and sleep disturbances● Carbohydrate cravings and weight gain
■ Phototherapy for SAD: increased exposure to light improves mood in SAD (and also for unipolar depression)
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