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Chapter 16

Chapter 16 Textbook Notes - Psychological Disorders

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Ayesha Khan

Notes From Reading CHAPTER 16:P SYCHOLOGICAL DISORDERS (PGS.456-483) Introduction - Psychological Disorders – An unusual pattern of thinking, feeling, and behaving that is harmful to the self or to others LO1: Describe the major symptoms of schizophrenia Schizophrenia - Schizophrenia – A group of disorders characterized by hallucination, delusion, cognitive impairment, mood disturbance, and social withdrawal o Positive Symptom – An abnormal behaviour, such as hallucination and delusion, that does not occur in healthy individuals but occurs in people with schizophrenia o Negative Symptom – A normal and expected behaviour that is absent due to schizophrenia - Hallucination – A false or distorted perception of objects or events - Delusion – A false belief or opinion that is strongly held in spite of conclusive, contradictory evidence - Most cases of schizophrenia are diagnosed for the first time in individuals between the ages of 18 an 25 years of age o But a sizeable minority of cases appear for the first time after age 40 o Men and women are equally likely to develop schizophrenia LO2: Summarize the possible causes and treatments of schizophrenia Genetics of Schizophrenia - Concordance Rate – The statistical probability that one individual will share a trait with another individual, typically a twin or other related person o In schizophrenia, the concordance rate is about 50 % in identical twins, and 17% in fraternal twins o That odds that a person will develop schizophrenia increases if someone in the family is diagnosed - Susceptibility genes for schizophrenia overlap with those implicated in bipolar disorder - Sccades – The rapid eye movement that occurs when an individual is visually tracking a movement stimulus o Patients with schizophrenia and some of their family members may show intrusions of saccades during smooth-pursuit tasks o These abnormal eye movements might represent deficits in executive cognitive functions, normally carried out by the frontal lobes, and in goal-related behaviour Environmental Contributions to Schizophrenia - Environmental influence may arise from poverty, poor nutrition, and the stress related to racism - Rate of schizophrenia are somewhat higher in urban environments o Living in an urban area also increases marijuana use, and it might represent the efforts of an individual to self-medicate for schizophrenia - Prenatal environmental facts might play a role in the development of schizophrenia o Development of schizophrenia in offspring is correlated with mothers’ difficulties during pregnancy (bleeding and diabetes), abnormal fetal development (low birth weight and small head circumference), and birth complications (emergency caesarean section, lack of oxygen) - Mother’s exposure to famine or viral infection during her pregnancy can contribute o People born between January and April (in the northern hemisphere) are slightly more likely than people born in other seasons to be diagnosed with schizophrenia o Most likely because mothers are exposed to viruses due to the cold weather Brain Structure and Function in Schizophrenia - Patients with schizophrenia have enlarged ventricles o Represents a loss of neuron in adjacent areas - The hippocampus has been found to be smaller than normal in some individuals o Given the importance for the hippocampus is in memory and cognition, this lack of organization might account for some of the deficits in reasoning and thought Notes From Reading CHAPTER 16:P SYCHOLOGICAL D ISORDERS (PGS .456-483) - Lower activity in the frontal lobes, or hypofrontality, is associated with some of the negative symptoms of schizophrenia, such as mood disturbance and social withdrawal - Brains of people with schizophrenia are more symmetrical in structure and function than brains of healthy individuals o People with schizophrenia are more likely to have ambiguous handedness o Can be considered occasional failure of normal brain lateralization Biochemistry of Schizophrenia - It is difficult to make a clinical distinction between a person with schizophrenia and a person who has chronically abused stimulant drugs such as amphetamine or cocaine - Typical Antipsychotic Medication – A dopamine antagonist that is used to treat schizophrenia or psychosis resulting from the use of dopamine agonists, such as cocaine and amphetamine - Increases in dopamine activity are associated with psychosis, and decreases in dopamine activity are associated with a reduction in psychosis - Phenothiazine – One of a major group of dopamine antagonists used in the treatment of psychosis o One quarter of all patients with schizophrenia fail to respond favourably to treatment with dopamine antagonists, such as the phenothiazine - Atypical Antipsychotic Medication – One of several new medications used to treat schizophrenia that are not dopamine antagonists o Provides a relief from schizophrenia by acting on neurotransmitters other than dopamine - Glutamate and dopamine systems often interact in the brain, and increasing dopamine or decreasing glutamate should result in similar behavioural outcomes o Glutamate’s important roles in the normal functioning of the hippocampus and frontal lobes, areas of the brain where abnormalities occur in schizophrenia - The drug phencyclidine (PCP or “angel dust”) is capable of producing several schizophrenia-like symptoms, including auditory hallucinations o PCP not only stimulates dopamine release but also blocks the NMDA glutamate receptor o Psychosis due to PCP use responds favorably to treatment with dopamine antagonists Treatment of Schizophrenia - Treatment for schizophrenia was revolutionized with the discovery of the typical antipsychotics; the first of these to be used were the phenothiazines o Chlorpromazine – A commonly prescribed dopamine antagonists, also known as Thorazine o Penothiazines were effective in treating the symptoms of schizophrenia o Typical antipsychotics primarily benefit patients with schizophrenia by reducing positive symptoms o Negative symptoms, such as social withdrawal and emotional disturbance, do not appear to respond much to these medications - Tardive Dyskinesia – A chronic disorder, characterized by involuntary, jerky movements, that occurs as the result of long-term treatment with antipsychotic medications o Patients experience tremors and involuntary movements, especially in the face and tongue - Hypersensitivity to dopamine, disturbances of balances between dopamine and acetylcholine, interference with GABA-dependent inhibition in pathways linking the substantia nigra to the basal ganglia, and excitotoxicity - More than half of all patients today are treated with new atypical antipsychotic medications such as olanzapine, clozapine, and rispiridone o Clozapine has a stronger effect on serotonin receptors than on dopamine receptors - Advantage of these newer medication: reduction in negative symptoms and positive symptoms in some patients - Disadvantage: produce weight gain and diabetes in many patients, and still carry the risk of producing tardive dyskinesia - In cases where hallucinations are not responsive to medication, magnetic stimulation of the brain can reduce instance of auditory hallucination for up to 15 weeks LO3: Compare and contrast the main features of major depressive disorder and bipolar disorder Notes From Reading CHAPTER 16:P SYCHOLOGICAL DISORDERS (PGS.456-483) LO4: Summarize the possible causes and treatments of major depressive disorder and bipolar disorder Mood Disorders - Major Depressive Disorder (MDD) – A disorder in which intense feelings of sadness, hopelessness and worthlessness persist a minimum of two weeks o Experience lengthy, uninterrupted periods of depressed mood and loss of pleasure in their normal activities - Bipolar Disorder – A mood disorder characterized by alternating cycles of mania and depression o Individual alternates between periods of unrealistically elevated mood (mania), and periods of profound depression Major Depressive Disorder - DSM-IV defines major depressive episodes as periods of pervasive sadness that last for at least 2 weeks - People with MDD often withdraw from activities they previously found rewarding, including hobbies and sex - Affects eating habits, energy levels, sleep, and cognition Genetics of Depression - Based on analyses of twins, the heritability of depression appears to be around 33% - Adoption studies support a role for gens in the development of depression - Variations in the serotonin transporter genes, which comes in both long and short forms, do not by themselves predict the development of MDD o Those with one or two copies of the short form of the gene were much more likely to develop depression than two with two copies of the long form Environment Factors and Depression - Pretnatal events might contribute to a vulnerability to mood disorder - Stress often serves as a trigger for depressive episodes o Stress might lead to depression by leading to a larger and prolonged release of cortisol, particularly in people with short versions of the serotonin transporter gene Brain Structure and Function in MDD - Reduced volumes in the hippocampus and the orbitofrontal cortex have been observed in the brains of patients with MDD - During decision-making tasks, patients with MDD showed abnormal activation in the anterior cingulate cortex (ACC) relative to healthy controls - Depression is correlated with reduced activity in the left frontal lobe and increased activity in the right frontal lobe o Damage to the left frontal lobe from a stroke or another pathological condition typically produces a profound depression in patient o Damage to the right frontal lob appears to have less impact on mood - Some people whoa re depressed enter their first cycle of REM sleep after approx. 45 ins of sleep rather than normal 90 minutes o Stage 3 and 4 of NREM sleep are reduced, and the lighter stages 1 and 2 ar more prominent - Further evidence for a relationship between sleep and depression comes from the effects of selective REM deprivation on mood o When people are awakened each time they enter REM sleep, they report a significant reduction in depression Biochemistry of Depression - Selective Serotonin Reuptake Inhibitors (SSRIs) – A type of medication, used to treat major depressive disorder and related conditions, that interferes with the reuptake of serotonin at the synapse - Cortisol is one of the several glucocorticoids released by the adrenal glands in response to both circadian rhythms and stress related activity in the so-called hypothalamic pituitary adrenal (HPA) axis o Peak release of cortisol occurs earlier in the cycle, lending further support to the connection between irregular circadian rhythms and depression Notes From Reading CHAPTER 16:P SYCHOLOGICAL D ISORDERS (P GS.456-483) - Abnormalities in glucocorticoid metabolism can be tested directly by using the dexamethasone suppression test (DST) o When dexamethasone is injected into healthy participants, cortisol secretion is suppressed o Following successful treatment with medication, these patients respond normally to the DST Treatment of Depression - Effective antidepressant medications appear to share the ability to stimulate neurogenesis in the hippocampus - Cognitive-behavioural therapy, combining behavioural therapy typically produces the best long-term outcomes for patients with depression - Electroconvulsive Shock Therapy (ECT) – A treatment of mood disorders in which convulsions are produced by the passage of an electric current through the brain o Patient is anesthetized and given a muscle relaxant while seizures are induced by electricity applied through electrodes on the head o 6-12 treatments are given, where ECT appears to stimulate neurogenesis in the hippocampus - There is no evidence that the procedure produces permanent brain damage Bipolar Disorder - Bipolar disorder is characterized by alternating cycles of depression and mania - Mania – An emotional state characterized by abnormally elevated, expansive, or irritable mood o Symptoms: inflated self-esteem, decreased need for sleep, higher-than-normal verbal output, flight of ideas, distractibility, increased goal-directed activity and excessive involvement in pleasure-seeking activities - Males and females are equally likely to be diagnosed with bipolar disorder - Bipolar disorder has been linked to enhance creativity - Patients with bipolar disorder scored similarly on tests of creativity to the healthy controls in creative disciplines and higher than either those with MDD or controls in noncreative disciplines Causes of Bipolar Disorder - Genes appear to play a more significant role in bipolar disorder than in MDD - Concordance rates among identical twins are often reported to be as high as 85%, in contrast to the 30-40% usually observed in major depressive disorder - Adoption studies also support a powerful role in genetics in he development of bipolar disorder - Dietary omega-3 fatty acids, generally found in fish, might provide some protection from bipolar disorder Brain Structure and Function in Bipolar Disorder -
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