Weissman et al (2005)

• Type of study


  Family studies
• Family studies (generation)


  Three generations
• Participants


  161 total (inclusive of three generations)
• Aim


  Study the potential genetic nature of Major Depressive Disorder
• Period

  20
• 'Depressed' sample


  Selected from an outpatient clinic with a specialisation in the treatment of mood disorders.
• 'Non-depressed' sample


  Selected from same community
• Procedure


  The original sample (grandparents) was interviewed four times during this period.
• Data collection


  Collected from clinicians, blind to past diagnoses.
• Triangulation


  Research triangulation - children were evaluated by two experienced clinician (child psychiatrist + psychologist). Inter-reliability: 0.82 for MDD, 0.65 anxiety, 0.94 for alcohol dependency.
• Results


  High rates of psychiatric disorders in grandchildren with two generations of major depression (by 12y, 59.2% were already showing signs of psychiatric disorder).
• Trend observed


  Increased risk of disorder in children if there were two affected past generations, as compared to those with one affected past generation.
• Trends observed


  Parent's depression severity correlated with increased rate of mood disorders.
• Trends observed


  If parents were depressed but there was no history of depression, there was no significant effect of parental depression on grandchildren.
• Strengths


  Longitudinal increases reliability of data, large sample, researcher triangulation.
• Limitations


  Amount of time spent with parents/grandparents can be confounding, no actual genotype studied.