Weissman et al (2005)

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Study Note: Weissman et al. (2005) - Depression and Genetic Link

Aim

The study aimed to investigate the potential genetic nature of Major Depressive Disorder (MDD) across three generations within families.

Procedure

• Design: Longitudinal kinship study.
• Sample: 161 grandchildren, their parents, and grandparents.
• Duration: 20-year period.
• Selection: Grandparents with depression were selected from an outpatient clinic specializing in mood disorders; non-depressed participants were from the same local community.
• Assessment: Parents and children were interviewed four times over the study period. The third generation (grandchildren) was also included.
• Evaluation Method: Clinicians, unaware of past depression diagnoses, conducted evaluations. Children were assessed by a child psychiatrist and a psychologist.

Results

• High Rates of Psychiatric Disorders: 59.2% of grandchildren with two generations of major depression showed signs of psychiatric disorders by age 12, predominantly anxiety disorders.
• Increased Risk with Depressed Grandparents and Parents: The risk of disorders was higher in children if both grandparents and parents had depression.
• Parental Depression Severity Correlation: The severity of a parent's depression correlated with a higher rate of mood disorders in children.
• Parental Depression Without Grandparental History: No significant effect on grandchildren if only the parent, but not the grandparent, had a history of depression.

Conclusion

The study suggests a strong genetic component in the transmission of Major Depressive Disorder, as evidenced by the increased prevalence of psychiatric disorders in grandchildren when both the previous generations had depression.

Critical Thinking

• Strengths:
  • Longitudinal design provides robust data over time.
  • Multi-generational approach offers comprehensive insights.
  • Use of clinicians blind to past diagnoses reduces bias.
• Limitations:
  • The sample may not be representative of the general population.
  • The study focuses on one specific disorder, limiting the generalizability to other psychiatric conditions.
  • Potential environmental factors influencing depression were not deeply explored.

Relation to Gene and Behavior

This study demonstrates a clear relationship between genetic factors and behavior, particularly in the context of depression. The increased prevalence of psychiatric disorders in grandchildren with a family history of depression across two generations strongly indicates a genetic link in the transmission of depressive behaviors and susceptibilities. This finding underscores the importance of considering genetic factors in understanding and treating psychiatric disorders like Major Depressive Disorder.