Alcohol use disorders and risk of Parkinson’s disease: findings from a Swedish national cohort study 1972–2008

BACKGROUND Alcohol has been suggested to be either protective of, or not associated with Parkinson's disease (PD). However, experimental animal studies indicate that chronic heavy alcohol consumption may have dopamine neurotoxic effects relevant for PD. We studied the association between diagnosed alcohol use disorders and PD. METHODS All individuals in Sweden admitted with a diagnosis of an alcohol use disorder or appendicitis (reference group) between January 1, 1972 and December 31, 2008 were identified through the Swedish National Inpatient Register, and followed for up to 37 years for a diagnosis of PD. We estimated hazard ratios (HR) with 95% confidence intervals (CI) and adjusted for age and sex. RESULTS We found 1,741 (0.3%) cases of PD in the cohort of 602,930 individuals, 1,083 (0.4%) among those admitted with an alcohol use disorder and 658 (0.2%) of the individuals admitted with appendicitis. The mean follow-up time was 13.6 and 17.1 years, respectively. The HR for PD associated with an alcohol use disorder was 1.38 (CI 1.25-1.53) adjusted for age and sex. When the risk was estimated in age groups for first hospital admission with PD the highest risk was observed in the lowest age group, ≤44, HR 2.39 (0.96-5.93), adjusted for age at exposure and sex. CONCLUSIONS A history of an alcohol use disorder conferred an increased risk of admission with a diagnosis of Parkinson's disease in both women and men. In particular, the risk seemed higher at lower ages of first admission with Parkinson's disease.