Weissman et al (2005)

• Aim


  To investigate potential genetic nature of major depressive disorder
• Method


  Prospective study

  
  

  161 grandparents, parents, grandchildren
• Procedure


  Duration: 20 year period

  
  

  Looked at families at higher or lower risk for depression

  -> Depressed patients selected from the outpatient clinic with specialisation of treatment of mood disorders

  -> Non-depressed patients selected from same local community

  
  

  Grandparents and parents interviewed 4 times for 20 years

  Children evaluated by 2 experienced clinicians
• Results

  2 generations showing symptoms of major depression

  -> higher rate of psychiatric disorders in children

  
  

  2 generations depressed -> higher risk of disorder

  
  

  Parent depressed but grandparent not depressed -> No significant effect or parental depression on grandchildren
• Conclusion

  Family history of mental illness for 2 or more generations -> higher risk of psychiatric disorder

  
  

  Strong case for genetic component since children more likely to display symptoms of psychiatric disorders when both grandparents and parent did
• Type of study


  Kinship (family) study
• Strengths

  · The study is longitudinal, increasing the reliability of the data.

  · The use of researcher triangulation increases the credibility of the findings.

  A sample of 161 children is a large sample
• Limitations


  · The association between parental MDD and child diagnosis is moderated by grandparental MDD status. The amount of time that a child spent with a health grandparent may be a confounding variable in the study.

  · Although family (kinship) studies indicate a potential genetic link to behavior, there is no actual genotype studied.

  Correlation only- no cause and effect