Which study suggested that individuals with the 5-HTTT gene reacted to stressful life events with more depressive symptoms?

• A. Caspi et al. (2003)
• B. Kendler et al. (1993)
• C. Plomin et al. (1986)
• D. Watson et al. (2009)

Answer: (A)

The question tests gene-environment interaction, specifically how a genetic variant in the serotonin transporter gene (5-HTTLPR) can influence sensitivity to stressful life events in relation to depressive symptoms. Caspi and colleagues conducted a long-term study of a large cohort and found that individuals with at least one short allele of 5-HTTLPR showed more depressive symptoms as stressful life events increased, whereas those with two long alleles did not show this pattern. This directly demonstrates that a specific genetic factor moderates the impact of environmental stress on depression, illustrating the diathesis-stress (gene-environment interaction) model in action. Other studies listed focus on heritability or different topics rather than this specific interaction between 5-HTTLPR and stress on depression, so they don’t address this particular mechanism.