Previous research has revealed elevated risks for aggression among children who carry short alleles of the serotonin transporter gene (5-HTTLPR) and are exposed to stress. However, it has not been known whether the associations between stress, genotype, and aggression continue over the transition into adulthood, whether chronic and acute stress have different effects, or whether stress predicts increased aggression over significant developmental periods. To find out, Conway et al. (2012) applied structural equation modeling to longitudinal data from 381 Australians to test relations between (a) age 15 scores on the Aggressive Behavior syndrome of the CBCL/6-18, TRF, and YSR; (b) age 20 scores on the Aggressive Behavior syndrome of the YASR and YABCL (predecessors of the ASR and ABCL) and the Buss Aggression Questionnaire; (c) chronic and acute stress scored from mother and participant interviews at age 20; and (d) 5-HTTLPR genotypes.
It was found that participants who had been subjected to high chronic stress and who had either one or two short alleles of the 5-HTTPLR serotonin transporter gene obtained significantly higher age 20 aggression scores than other participants. Furthermore, the significant effect remained after partialing out age 15 CBCL/6-18, TRF, and YSR Aggressive Behavior scores. In other words, the significant effect reflected increases in aggression from age 15 to 20 among participants who had experienced chronic stress and carried short alleles of the 5-HTTLPR gene. Effects were similarly significant for both genders, and stress levels did not differ significantly by genotype. The authors concluded that “the influence of 5-HTTLPR on neural pathways mediating executive control or affect regulation may predispose s (short allele) carriers to more intense and persistent affective, cognitive, and behavioral manifestations of aggression in the face of stress” (p. 61).
Conway, C.C., Keenan-Miller, D., Hammen, C., Lind, P.A., Najman, J.M., & Brennan, P. A. (2012). Coaction of stress and serotonin transporter genotype in predicting aggression at the transition to adulthood. Journal of Clinical Child & Adolescent Psychology, 41, 53-63.