Biological - Genetics

• What are the three possible causes of schizophrenia according to the Biological Approach?


  Genetic explanations, the dopamine hypothesis, and neural correlates
• Why do researchers test whole families for their genetics in relation to schizophrenia?

  To examine concordance rates between families and twins to see if schizophrenia is hereditary
• What did Parmas (1993) find in his longitudinal family study regarding children with a schizophrenia mother?


  16% of children with a schizophrenia mother developed the disorder compared to 2% of controls
• What environmental influences have been found to be a cause of schizophrenia according to Morgan et al. (2017)?


  Birth complications
• What relationship did Gottesman (1991) find regarding genetic similarity and schizophrenia risk?


  There is a strong relationship between the degree of genetic similarity and shared risk of schizophrenia
• What does it mean that schizophrenia is thought to be polygenic?

  It means that many different genes contribute to an increased risk of developing it
• What does aetiologically heterogeneous mean in the context of schizophrenia?

  It means different combinations of genes are implicated in the disorder
• How many genetic variations associated with schizophrenia did Ripke et al. (2014) find?

  108 genetic variations
• What is the significance of MZ twins showing a higher concordance rate than DZ twins in schizophrenia research?

  It suggests that the behavior is genetic
• What were the concordance rates for MZ and DZ twins found by Joseph (2004)?


  40.4% for MZ twins and 7.4% for DZ twins
• What is the purpose of adoption studies in schizophrenia research?


  To combat the issue of 'shared environment' that twins endure
• What did Tienari (2000) find in his research on adoptees with schizophrenia mothers?

  11 (6.7%) of adoptees with schizophrenia mothers received a schizophrenia diagnosis
• What did Kety (1992) find regarding prevalence rates of schizophrenia among genetic relatives compared to adopted relatives?


  Prevalence rates for schizophrenia were 10 times higher among genetic than adopted relatives
• What are the supports and challenges for genetic explanations of schizophrenia based on various studies?


  Supports genetic explanations:

  • Joseph (2004)
  • Gottesman (1991)
  • Ripke et al. (2014)
  • Parmas (1993)

  
  

  Challenges genetic explanations:

  • Tienari (2000)
  • Kety (1992)
  • Diathesis-stress model
  • Blind studies showing lower concordance
  • Common family rearing patterns
  • Morgan et al. (2017)