Abstract
Recently, I suggested that the environment can act as a mediator of genetic influences in a process termed Gene-Environment-Trait correlations (rGET). I further hypothesized that socioeconomic status (SES) may mediate the negative genetic correlation found between cognitive ability and depression. This hypothesis was based on previous research showing that SES is associated with both cognitive ability and depression. Thus, in the current study I aimed to test for an rGET in which genetic influences on cognitive ability were associated with depressive symptoms via SES. Educational attainment (EA) was used as a proxy for cognitive ability, due to the high genetic correlation between the phenotypes and the highly powerful genome-wide association study (GWAS) available for EA. Summary statistics from the EA GWAS were utilized to calculate EA polygenic scores, and mediation analyses were performed to examine if the EA polygenic scores predicted depressive symptoms via SES. Two independent samples were used for the analyses: 522 non-Hispanic Caucasian university students from the Duke Neurogenetics Study (DNS; 277 women, mean age 19.78±1.24 years) and 5,243 white British volunteers (2,669 women, mean age 62.30±7.41 years) from the UK biobank (UKB). Results indicated a significant mediation in both samples, wherein higher EA polygenic scores predicted higher SES, which in turn predicted lower depressive symptoms. Current findings suggest that some of the genetic correlates of depression represent environmental influences and consequently that public policy aiming to reduce socioeconomic inequalities may not only relieve the individual and societal burden of depression, but also decrease the genetic risk for depression.
Competing Interest Statement
The authors have declared no competing interest.
Footnotes
Introduction and discussion.