Interaction between the 5-HTTLPR serotonin transporter polymorphism and environmental adversity for mood and anxiety psychopathology: evidence from a high-risk community sample of young adults

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Abstract
Previous research examining gene–environment interaction (G×E) with regard to vulnerability to depression and anxiety has yielded conflicting results. The present study was designed to further investigate G×E between 5-HTTLPR and exposure to environmental adversity, using different phenotypic and genotypic characterizations as well as different types of adversity within a prospective study design. Data were available from an ongoing epidemiological cohort study following the outcome of early risk factors from birth to adulthood. At age 19 yr, 309 participants (142 males, 167 females) were characterized on measures of depression and anxiety through interview and questionnaire (DSM-IV diagnosis, Beck Depression Inventory, Harm Avoidance). Environmental adversity was assessed at birth (family adversity), and at age 19 yr (stressful life events). Bi- and tri-allelic 5-HTTLPR genotypes were obtained from genomic DNA. Results indicated that depression and anxiety in 19-yr-olds were strongly associated with both family adversity and stressful life events. Individuals with the LL genotype of 5-HTTLPR who were exposed to high family adversity displayed significantly higher rates of depressive or anxiety disorders and had more depressive symptoms than those without either condition. This G×E replicates recent findings from an epidemiological cohort study of adolescents but is in contrast to many previous reports suggesting an interaction with the S allele. No evidence for G×E was obtained with regard to current stressful life events and trait anxiety. One possible source for the conflicting findings might be attributed to heterogeneity in depression phenotypes and environmental adversity.