Serotonin Transporter Gene Polymorphism (5-HTTLPR) and Anxiety Reactivity in Daily Life: A Daily Process Approach to Gene-Environment Interaction

Address correspondence and reprint requests to: Howard Tennen, PhD, E-mail: tennen{at}nso1.uchc.edu.

	Abstract

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 L_AL_A 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-environment 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 1 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.

Key Words: serotonin transporter, anxiety, stress, reactivity, daily diary