Key Research - Gottesman

• What is the background?

  • Previous research results varied - offspring of both parents with schizophrenia ranged between 28% - 58% risk and ranged between 22% - 80% for manic depressive disorder
  • Gottesman proposed studies of outcome of parents with homotypic disorders and suggested there may be an overlap between phenotypes of bipolar and schizophrenia
  • Previous research where both parents have disorder gave small samples and lack generalisability
• What is the aim?

  • To investigate the importance of genetic influence on offspring where both parents have a psychiatric disorder
  • To build upon previous research and attempted to have a larger sample size by using reported diagnoses from Danish Central Psychiatric Register
• What was the method?

  • National cohort study in Denmark
  • Secondary data
• What was the sample?

  • 2.7 million people in Denmark alive in 1968-1997 with an identifiable mother and father from the Civil registration system
  • Restricted to people who were 10 or over before 2007
• What was the procedure?

  • People diagnosed with schizophrenia, bipolar, unipolar depressive disorder were identified from the Psychiatric Central Register through groups of parents who were admitted into a psychiatric facility from 1970-2007
  • Calculated incidence when both parents were admitted
  • Calculated incidence  when only 1 parent admitted
  • Calculated incidence when neither parent was admitted
  • Calculated when 1 parent admitted for schizophrenia and the other bipolar
  • Parents and children mutually exclusive because they have been admitted more than once for different reasons
• What are evaluations of the procedure?

  • ICD 8 – 10 to diagnose (less reliable as different versions as less consistent)
  • Ethical as confidential and not identifiable
  • Did not need informed consent as on register
• What were the findings and conclusions?

  • If both parents have schizophrenia or bipolar there is an increased risk of offspring getting a psychiatric diagnosis  
  • Higher chance of offspring getting a psychiatric diagnosis if both parents have schizophrenia instead of both parents having bipolar  
  • Provides evidence for genetic overlap between schizophrenia and bipolar because if heritability of one increases it also increased for other disorders suggesting shared genetic factor