War Zone Stress Interacts With the 5-HTTLPR Polymorphism to Predict the Development of Sustained Attention for Negative Emotion Stimuli in Soldiers Returning From Iraq

Abstract

Biased attention toward negative stimuli is a known vulnerability for affective psychopathology. However, factors that contribute to the development of this cognitive bias are largely unknown. Variation within the serotonin transporter gene (i.e., 5-HTTLPR) is associated with increased susceptibility to environmental influence and biased processing of negative stimuli. Using a passive viewing eye-tracking paradigm, this study examined gaze fixation for emotion stimuli in 91 U.S. Army soldiers before and after deployment to Iraq. In addition, participants underwent genetic assay and provided in situ measures of war zone stress exposure. 5-HTTLPR short allele homozygotes were more likely than other genotype groups to develop a gaze bias toward negative stimuli as a function of increasing war zone stress, even when controlling for postdeployment posttraumatic stress disorder and depression severity. Short allele homozygotes appear especially sensitive to environmental influence, which likely contributes to the development of cognitive vulnerability to anxiety and mood disorders.