Educational attainment and mental health conditions: a within-sibship Mendelian randomization study

ImportanceObservational studies have demonstrated consistent protective effects of higher educational attainment (EA) on the risk of suffering mental health conditions (MHC). Determining whether these beneficial effects are causal is challenging given the potential role of dynastic effects and demographic factors (assortative mating and population structure) in this association. ObjectiveTo evaluate to what extent the relationship between EA and various MHC is independent from dynastic effects and demographic factors. DesignWithin-sibship Mendelian randomization (MR) study. SettingOne-sample MR analyses included participants data from the Trondelag Health Study (HUNT, Norway) and UK Biobank (United Kingdom). For two-sample MR analyses we used summary statistics from publicly available genome-wide-association-studies. Participants61 880 siblings (27 507 sibships). ExposureYears of education. Main outcomesScores for symptoms of anxiety, depression and neuroticism using the Hospital Anxiety Depression Scale (HADS), the 7-item Generalized Anxiety Disorder Scale (GAD-7), the 9-item Patient Health Questionnaire (PHQ-9), and the Eysenck Personality Questionnaire, as well as self-reported consumption of psychotropic medication. ResultsOne standard deviation (SD) unit increase in years of education was associated with a lower symptom score of anxiety (-0.20 SD [95%CI: -0.26, -0.14]), depression (-0.11 SD [-0.43, 0.22]), neuroticism (-0.30 SD [-0.53, -0.06]), and lower odds of psychotropic medication consumption (OR: 0.60 [0.52, 0.69]). Estimates from the within-sibship MR analyses showed some attenuation, which however were suggestive of a causal association (anxiety: -0.17 SD [-0.33, -0.00]; depression: -0.18 SD [-1.26, 0.89]; neuroticism: -0.29 SD [-0.43, -0.15]); psychotropic medication consumption: OR, 0.52 [0.34, 0.82]). Conclusions and RelevanceAssociations between EA and MHC in adulthood, although to some extend explained by dynastic effects and demographic factors, overall remain robust, indicative of a causal effect. However, larger studies are warranted to improve statistical power and further validate our conclusions. Key pointsO_ST_ABSQuestionC_ST_ABSAre the protective effects of higher educational attainment on the risk of suffering mental health conditions independent from familial (i.e.,dynastic effects) and demographic factors (i.e., assortative mating and population structure)? FindingsAlthough to some extend explained by familial and demographic factors, overall the protective effects of higher educational attainment remain robust. MeaningOur findings are consistent with those of previous observational studies, which suggests that higher educational attainment may causally reduce the risk of suffering a mental health condition.