Nature of the Causal Relationship Between Academic Achievement and the Risk for Alcohol Use Disorder

Abstract

We evaluated the claim that interventions to improve academic achievement can reduce the risk for alcohol use disorder (AUD). Using nationwide data for individuals born in Sweden from 1972 to 1981 (n = 930,182), we conducted instrumental variable and co-relative analyses of the association between academic achievement and AUD with a mean 21.4-year follow-up. Our instrument, used in the instrumental variable analyses, was month of birth. Co-relative analyses were conducted in cousins, full siblings, and monozygotic twins discordant for AUD, with observed results fitted to a genetic model. The academic achievement-AUD association was modeled in Cox regression. AUD was assessed using national medical, criminal, or pharmacy registries. Later month of birth was significantly associated with poorer academic achievement. Lower standardized academic achievement had a strong relationship with the risk for subsequent AUD registration: hazard ratio (HR) [per SD] = 2.14 [2.11, 2.17]. Instrumental variable analysis produced a substantial but moderately attenuated association: HR = 1.52 [1.28, 1.80]. Controlling for modest associations between month of birth and parental education and AUD risk reduced the association to HR = 1.43 [1.20, 1.69]. Our genetic co-relative model fitted the observed data relatively well and estimated the academic achievement-AUD association in monozygotic twins discordant for academic achievement to equal an HR of 1.44 [1.35, 1.52]. Results were broadly similar when analyzed separately in males and females. Two distinct methods with different assumptions produced results suggesting that the association observed between academic achievement at age 16 and the risk for AUD into middle adulthood is partly causal, thereby providing support for interventions to improve academic achievement as a means to prevent later AUD risk.