Weissman et al (2005)

• Aim: 

  To investigate the potential genetic nature of Major Depressive Disorder (MDD) across three generations.
• Method:

   Longitudinal family study
• Participants:

  • 161 grandchildren and their parents and grandparents
  • High and low-risk families for depression
  • Original sample selected from an outpatient mood disorder clinic and local community
• Procedure:

  1. Study conducted over 20 years
  2. Original sample interviewed four times
  3. Data collected by clinicians blind to past diagnoses
  4. Researcher triangulation used (two experienced clinicians evaluated children)
  5. Inter-rater reliability measured for various disorders
• Results:

  1. High rates of psychiatric disorders in grandchildren with two generations of major depression
  2. 59.2% of grandchildren showed signs of psychiatric disorder by age 12
  3. Increased risk of disorders in children if both grandparents and parents had depression
  4. Severity of parent's depression correlated with increased rate of mood disorders in children
  5. No significant effect on grandchildren if only parents were depressed (without grandparental history)
• Key Findings:

  • Suggests a potential genetic component to Major Depressive Disorder
  • Highlights the importance of multi-generational studies in understanding mental health disorders
• Strengths:

  1. Longitudinal design increases data reliability
  2. Use of researcher triangulation enhances validity and reliability
  3. Large sample size (161 children)
  4. Blind assessment by clinicians reduces bias
• Limitations:

  1. Potential confounding variable: time spent with healthy grandparents
  2. No actual genotype studied, only familial patterns
  3. May need further research to confirm reliability of findings