UI PSYC 311 - Causes of Schizophrenia

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1Listen to the audio lecture while viewing these slidesPsychology 311Abnormal Psychology1Causes of Schizophrenia2Psyc 311 – Abnormal PsychologyCauses of Schizophrenia• Actual cause is not known• Appears to be an interaction between vulnerabilities and environmental stress3Psyc 311 – Abnormal PsychologyMany Different Hypotheses• Genetics•Prenatal Factors• Dopamine Hypothesis• Schizophrenic Spectrum Hypothesis• Diathesis Stress Model4Psyc 311 – Abnormal PsychologyGenetic Contributions• The closer the relative, the higher the probability for schizophrenic• Highly probable schizophrenia is genetic• Is probably not caused by one gene• Would show in all monozygotic twin studies.• Is probably caused by the combination of several genes.• Not totally sure which ones• Has been identified with genes on Chromosome 22 and Chromosome 6.5Psyc 311 – Abnormal PsychologyPrenatal Factors Hypothesis• Individuals exposed to a Flu virus in second trimester had higher rates of schizophrenia than a control group not exposed.• High stress shown in widowed Finnish women • When Russia invaded Finland in 1959, women had higher schizophrenia rates• Birth complications correlated with schizophrenia• Suggests brain damage6Psyc 311 – Abnormal PsychologyNeurodevelopmental Model• Contends some abnormality may occur in prenatal neurological development•Example• Second semester• Cells migrate from original position to distant locations where they establish connections• Schizophrenics brains are different than “Normals”•More cells were in deeper layers of the cortex than the surface•Indicates neurons did not migrate as far as they should have27Psyc 311 – Abnormal PsychologyPrenatal Development Abnormalities• Reflected in • Minor physical anomalies•Malformed ears•Unusual spacing of tear ducts•Arched Palate of the mouth• Neuromotor anomalies •Many unusual expressions•May hold hands in unusual manner8Psyc 311 – Abnormal PsychologyDopamine Hypothesis •Contends: • Positive symptoms occur due to increased levels of Dopamine.• Get increased stimulation of Dopaminergic synapses• Excessive receptor activation is correlated with hallucinations9Psyc 311 – Abnormal PsychologySupport for Hypothesis• Drugs that increase dopamine levels (Amphetamine, Cocaine) can produce positive symptoms of schizophrenia• Drugs that block DA receptors also reverse schizophrenia• Can reduce positive symptoms in 80% of patients 10Psyc 311 – Abnormal PsychologySchizophrenic Spectrum Disorder Hypothesis• Contends schizophrenic patients often have relatives that are eccentric or have bizarre behaviors• May be a genetic inheritance• Combination of •emotional responses •cognitive behavior•some personality disorders11Psyc 311 – Abnormal PsychologyExample – Schizotypal Personality Disorder• Seems closest genetically to schizophrenia• Behaviors are milder forms of schizophrenia• Odd speech patterns• Social dysfunction•Aloofness• Odd communication•Suspiciousness12Psyc 311 – Abnormal PsychologyFamilies• Paranoid personality disorder• Schizoid personality disorder•Others• All appear in families with schizophrenia• Gene on chromosome 8 is linked to the spectrum of disorders and schizophrenia313Psyc 311 – Abnormal PsychologyFamily Studies are Useful • Allows you to look for schizophrenia or other disorders• Make a family tree of disorders• Can get an idea of the full spectrum of disorders14Psyc 311 – Abnormal PsychologyAssociative Mating• Tendency to choose a mate that is genetically similar than would be expected by chance•Result• Children from these marriages may end up with “double doses” of bad genes15Psyc 311 – Abnormal PsychologyGottesman (1991)• Conducted five studies of associative mating• Risk for children increases 46% vs. 17% with only one parent affected16Psyc 311 – Abnormal PsychologyTwin Studies• Allow you to control for hereditary factors•MZ twins • Higher concordance rates for schizophrenia• Problem only 50% have it•Conclusion – Heredity is not enough alone 17Psyc 311 – Abnormal PsychologyExamine When Twin Becomes Schizophrenic• Some studies - 5 years old• More studies – 13 years old• Most common age 14 - 1618Psyc 311 – Abnormal PsychologyAdoption Studies• Is another way to study hereditary factors• Child is not raised by biological parents• Show more schizophrenia419Psyc 311 – Abnormal PsychologyEnvironmental Factors•Contends• You can have a genetic or biological predisposition• Problem, what causes the disorder to express itself20Psyc 311 – Abnormal PsychologyDiathesis Stress Model (Zurbin, 1983)• Contends the disorder is an interaction of genetic and environmental factors• Is not a permanent disorder but a permanent vulnerability21Psyc 311 – Abnormal PsychologyCommunity Factors• More than 50 studies in US and Europe• People with lower SES are diagnosed more frequently with schizophrenia than people in middle or upper SES•Why?•Two theories•Social Selection Theory•Increased Stress Theory22Psyc 311 – Abnormal PsychologySocial Selection• Contends people who cannot make it in “normal” society gradually become lower in SES due to poor coping skills• May occur across generations• Result – A whole class of people become lower SES• Model points to flaws in the individual23Psyc 311 – Abnormal PsychologyIncreased Stress• Contends there are flaws in society itself• Focuses on the amount of stress experienced in different environments• Conflicting sides• Maybe the environment drew in lower functioning individuals than producing lower functioning individuals24Psyc 311 – Abnormal PsychologyConclusions•Many models• Lots of different ideas• Some evidence form each• Not solid for an particular model• Each have


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UI PSYC 311 - Causes of Schizophrenia

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