Dissecting the genetic overlap of education, socioeconomic status, and mental health

Socioeconomic status (SES) and education (EDU) are phenotypically associated with psychiatric disorders and behavior. It remains unclear how these associations influence the genetic risk for mental health traits and EDU/SES individually. Using information from >1 million individuals, we conditioned the genetic risk for psychiatric disorders, personality traits, brain imaging phenotypes, and externalizing behaviors with genome-wide data for EDU/SES. Accounting for EDU/SES significantly affected the observed heritability of psychiatric traits ranging from 2.44% h2 decrease for bipolar disorder to 29.0% h2 decrease for Tourette syndrome. Neuroticism h2 significantly increased by 20.23% after conditioning with SES. After EDU/SES conditioning, novel neuronal cell-types were identified for risky behavior (excitatory), major depression (inhibitory), schizophrenia (excitatory and GABAergic), and bipolar disorder (excitatory). Conditioning with EDU/SES also revealed unidirectional causality between brain morphology and mental health phenotypes. Our results indicate genetic discoveries of mental health outcomes may be limited by genetic overlap with EDU/SES.