Intergenerational continuity of depressive symptoms: genetic and environmental pathways.

Background: Depression runs in families, with both genetic and environmental mechanisms contributing to intergenerational continuity, though these mechanisms have often been studied separately. This study examined the interplay between genetic and environmental influences in the intergenerational continuity of depressive symptoms from parents to offspring.

Methods: Using data from the Dutch TRAILS cohort (n = 2201), a prospective, genetically informed, multiple-generation study, we examined the association between parents' self-reported depressive symptoms (reported at mean age of 41 years) and offspring depressive symptoms, self-reported nearly two decades later, in adulthood (mean age: 29 years). We assessed the role of genetic (polygenic scores for depressive symptoms in parents and offspring) and environmental mechanisms (parental warmth during adolescence) in explaining intergenerational continuity of depressive symptoms in separate and combined models.

Results: Parents' depressive symptoms, offspring genetic predisposition, and parental warmth were associated with an increased risk of depressive symptoms in offspring. In the combined model, parents' genetic predisposition was linked to their own depressive symptoms, which were linked to lower parental warmth, which, in turn, was linked to higher depressive symptoms in offspring, after accounting for offspring genetic predisposition, sex, age, and socioeconomic status.

Discussion: Both genetic and environmental mechanisms contribute to the intergenerational continuity of depressive symptoms independently and in interplay. Despite a significant effect, the influence of parental warmth was modest, suggesting limited covariation between this particular parenting measure and depressive symptoms, at least when assessed with large temporal distance.