Evaluating the causal relationship between educational attainment and mental health.

We investigate the causal relationship between educational attainment (EA) and mental health using two research designs. First, we compare the relationship between EA and seventeen psychiatric diagnoses within sibship in Dutch national registry data (N = 1.7 million), controlling for unmeasured familial factors. Second, we use two-sample Mendelian Randomization, which uses genetic variants related to EA or psychiatric diagnosis as instrumental variables, to test whether there is a causal relation in either direction. Our results suggest that lower levels of EA causally increase the risk of MDD, ADHD, alcohol dependence, GAD and PTSD diagnoses. We also find evidence of a causal effect in the opposite direction for ADHD. Additionally, we find inconsistent results for schizophrenia, anorexia nervosa, OCD, and bipolar disorder, highlighting the importance of using multiple research designs to understand the complex relationship between EA and mental health.