Serotonin transporter gene polymorphism (5-HTTLPR) and anxiety reactivity in daily life: A daily process approach to gene-environment interaction

Objective: To test whether individuals with at least one copy of the short (S) or long (L)(G) allele of the serotonin transporter polymorphism (5-HTTLPR) exhibit greater increases in anxiety, compared with LALA individuals, under periods of high daily stress. Although this common polymorphism in the serotonin transporter gene has been identified as a vulnerability factor for anxiety, findings in the literature are mixed. Discrepant findings could be explained by recent research showing that 5-HTTLPR is functionally triallelic (L-A versus L-G or S), rather than biallelic (L versus S). Mixed findings could also result from a lack of attention to diathesis-stress models, whereby genetic vulnerability is considered latent until activated by stress (gene-enviromnent interplay). Based on this model, we argue that genotype differences in anxiety should be stronger in the presence of stress. Methods: A total of 350 college students recorded their daily stressors and mood for two 30-day periods, separated by I year. Results: Across both years, diathesis-stress patterns were observed for reports of anxious mood as a function of 5-HTTLPR. Individuals with at least one copy of the S or L-G allele at 5-HTTLPR experienced elevated anxious mood on days with more intense stressors, as compared with those who were L-A homozygotes. Genotype differences in anxiety were less apparent on low stress days. No consistent allelic association of 5-HTTLPR was observed with any other mood states, trait anxiety, or neuroticism. Conclusion: Our findings highlight the potential value of focusing on genetic vulnerability in the context of everyday environmental triggers.