factors that warrant more detailed investigations to understand their complex relationship with BD.) In contrast, MR indicated that BD had bi-directional “causal” relationships with problematic alcohol use, longer sleep duration, and mood instability. Insights into the relationship of such behavioral correlates with BD may have future impact on clinical decision making in the prophylaxis or management of the disorder. Higher educational attainment has previously been associated with BD in epidemiological studies55,56, while lower educational attainment has been associated with schizophrenia and major depression71,72. Here, educational attainment had a significant positive effect on risk of BD and vice versa. Interestingly, MiXeR estimated that almost all variants that influence BD also influence educational attainment. The substantial genetic overlap observed between BD and the other phenotypes suggests that many variants likely influence multiple phenotypes, which may be differentiated by phenotype-specific effect size distributions among the shared influencing variants.
