Again breaking the empirical ground in G × E research, Caspi et al.5 were the first to show that the 5-HTTLPR moderates effects of stressful life events during early adulthood on depressive symptoms as well as on probability of suicide ideation/attempts, and of major depression episode at age 26 years. Individuals with two ‘s' alleles proved most adversely affected, whereas effects on l/l genotypes were weaker or entirely absent. Of special significance, given our focus on differential susceptibility, is that carriers of the s/s genotype scored best on the outcomes just mentioned when stressful life events were absent, though this was just as true among low-MAOA activity individuals in Caspi et al.,2 although not by very much.
