PSYC1011 Lecture 27: Abnormal Psychology - Causes of mental disorders
Causes of mental disorders
• There were 182 mental disorders in DSM-II (published 1968)
• Over 300 mental disorders in DSM-5 (published 2013)
• Some differences include:
o Homosexuality in DSM-II not DSM-5
o Koro in DSM5 (under Other Specified Obsessive-Compulsive and Related Disorders)
o Internet Gaming Disorder proposed as a 'Condition for Further Study' in DSM-5
• Which mental disorders exist is reality?
• Labelling theory
• Biological factors
• Environmental factors
• Biological and Environmental interactions
• Psychological factors
Genetics of psychopathology
• Mental illness tends to run in families
o Suggests genetic basis
o Twin studies - shares 100% of their genes
o Siblings - shares 50%
o
▪ Black bar is always higher than white bars - genetics is involved
o
▪ All are heritable, some are more heritable than others
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• Gene associations and mental disorders
o COMT and schizophrenia
▪ People with Velocardio-facial syndrome (VCFS) are missing the COMT gene on
chromosome 21
▪ VCSF patients show very high rates of schizophrenia (~25%)
▪ COMT involved in breaking down dopamine
• Intimately related to schizophrenia
o Fragile X and autism
▪ Fragile X caused by mutation of the X-chromosome
• Distinctive facial abnormality
▪ 20-60% of people with Fragile X syndrome also have autism
▪ Fragile X accounts for ~5% of autism diagnoses
• Neurochemistry and mental disorders
o Serotonin and depression
▪
▪ Lower levels of serotonin receptors
o Dopamine and schizophrenia
▪
▪ More production of dopamine than healthy people
• Brain abnormalities and mental disorders
o Brain structure
▪ Regions of reduced cortical thickness in bipolar I disorder
▪
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o Brain function
▪ Regions of hyperactivity in OCD
▪
o Limitations of biological accounts
▪ Even the most highly heritable mental disorder are a long way off being entirely
heritable
• Less than 50% chance of developing schizophrenia even if your identical twin
has the disorder
▪ Mental disorders are invariably polygenetic
• No single gene has found to be responsible for any mental disorder
▪
▪ No 100% reliable biomarkers for any mental disorders
▪ Biomarkers for psychopathology are only sensitive enough to distinguish between
groups, not between individuals
•
• Holes - ventricles - cell death around ventricles
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Causes of mental disorders: there were 182 mental disorders in dsm-ii (published 1968, over 300 mental disorders in dsm-5 (published 2013) Some differences include: homosexuality in dsm-ii not dsm-5, koro in dsm5 (under other specified obsessive-compulsive and related disorders) Labelling theory: biological factors, environmental factors, biological and environmental interactions, psychological factors. Intimately related to schizophrenia: fragile x and autism. Fragile x caused by mutation of the x-chromosome: distinctive facial abnormality, 20-60% of people with fragile x syndrome also have autism. Fragile x accounts for ~5% of autism diagnoses: neurochemistry and mental disorders, serotonin and depression. Environment: early life experiences influence subsequent psychopathological tendencies. Integrative approach: biological accounts of psychopathology are incomplete; environment plays a key role, diathesis-stress model. Individuals have genetic and biological vulnerabilities for developing mental disorders: these vulnerabilities may become activated in the presence of certain environmental stressors, the greater the underlying vulnerability, the less stress needed to trigger the disorder, nature and nurture.
