Adoption study - Kety

• Aim:

  To find out whether there is a genetic basis for schizophrenia 

  • in particular comparing the adoptive family and biological family of a schizophrenia sufferer to see if there is a higher rate of schizophrenia related illness amount biological relatives than adoptive relatives 
• IV:

  • Independent groups design as it looks at difference between biological and adoptive relatives of schizophrenia patients 
  • Looks at difference between schizophrenia suffers and control group who are mentally healthy 
  • Because adoption and schizophrenia are naturally occurring variables it is a natural experiment
• DV:

  The prevalence of schizophrenia related mental illness among  family members 
• Sample: opportunity sample

  • sample found from danish adoptive register in Denmark as well as mental heath register
  • All participants had been adopted 
  • 34 schizophrenic patients (two were monozygotic twins) taken from danish adoption register for Copenhagen 
  • Aged between 20-43 
  • Taken from a larger sample of 503 adoptees admitted to psychiatric hospitals with general mental illness 
• Groups based on diagnosis of schizophrenia 

  B1: 16 patients with chronic (long term) schizophrenia 

  B2: 7 patients with acute (short term or one off) schizophrenia 

  B3: 11 patients with borderline schizophrenia 
• 33 mentally healthy controls were selected from danish adoption registry 

  • controls were matched based on age, gender and age at which they were adopted and social class of adoptive family 
• • kety used family records to locate adoptive and biological relatives of participants as well as assessing all 463 of their mental status’s using mental heath register 
• • Panel of 4 danish psychiatrists used medical records to diagnose family members which was done blindly so the psychiatrist did not know wether records were from adoptive or biological family members 
• • Once diagnosis’s were made identity’s were revealed and assigned 
  • psychiatrists diagnosed family members in same category’s B1,B2 and B3
  • Some psychiatrists were uncertain due to only working from medical records so they used D1-D3 categories which was uncertain versions of the B category’s C=inadequate personality or schizoid 
• Kety concluded that there was to be a genetic component to schizophrenia as shown in results schizophrenic adoptees were more likely to have schizophrenia in their biological family than their adoptive family

  In addition their biological family were more likely to have schizophrenia 8.7% than controls 1.9% 
• results:

  their biological family were more likely to have schizophrenia 8.7% than controls 1.9%