Arguable assumptions, debatable conclusions - PubMed (original) (raw)

Figure 1

Results of multiple regression analyses estimating the association between number of stressful life events (between ages 21 years and 26 years) and the probability of major depressive disorder by age 26 as a function of serotonin transporter protein genotype. Among the 146 s/s homozygotes, 43 (29%), 37 (25%), 28 (19%), 15 (10%), and 23 (16%) study members experienced zero, one, two, three, and four or more stressful events, respectively. Among the 435 s/l heterozygotes, 141 (32%), 101 (23%), 76 (17%), 49 (11%), and 68 (16%) experienced zero, one, two, three, and four or more stressful events. Among the 264 l/l homozygotes, 79 (29%), 73 (28%), 57 (21%), 26 (10%), and 29 (11%) experienced zero, one, two, three, and four or more stressful events. The main effect of the serotonin transporter gene was not significant (_b_=−.15, SE = .14, z = 1.07, p = .29), the main effect of life events was significant (_b_=.37, SE=.06, _z_=5.99, _p_=.001), and the gene × environment interaction was in the predicted direction (_b_=−.19, SE=.10, _z_=1.91, _p_=.056). Life events predicted a diagnosis of major depression among s carriers (_b_=.52, SE=.16, _z_=3.28, _p_=.001 among s/s homozygotes, and _b_=.39, SE=.09, _z_=4.24, _p_=.001 among s/l heterozygotes) but not among l/l homozygotes (_b_=.16, SE=.13, _z_=1.18, _p_=.24). From Caspi et al., Influence of life stress on depression: moderation by a polymorphism in the 5-HTT gene. Science 2003;301:386–389. Reprinted with permission from AAAS.