Background: We recently described a preliminary association between the hypofunctional seven-repeat allele of the dopamine-4 receptor gene (DRD4) and increased maximal lifetime body mass index in women with seasonal affective disorder (SAD). In this study, we examined whether binge eating behavior mediated this putative association.
Methods: The study sample consisted of 131 women with winter SAD who reported increased intake of high-carbohydrate/high-fat foods during depressive episodes. We compared rates of binge eating behavior in the two genotypic groups defined by the presence or absence of the seven-repeat allele of DRD4.
Results: Consistent with our working hypothesis, the proportion of binge eaters was significantly greater in probands with the seven-repeat allele (18 of 46, 39.1%) than in probands without this allele (14 of 85, 16.5%) [chi(2)(1)= 8.32, p = .004; odds ratio = 3.25, 95% confidence interval 1.43, 7.41].
Conclusions: Pending replication in other samples, these results point to a genetic factor that could help in the early identification and treatment of women at higher risk for seasonal weight gain associated with binge eating behavior. At a theoretic level, the current results suggest a novel link between evolutionary models of seasonal weight gain on the one hand and the DRD4 gene on the other.