BACKGROUND: Previous prospective studies highlighted dairy intake as a risk factor for Parkinson's disease (PD), particularly in men. It is unclear whether this association is causal or explained by reverse causation or confounding.
OBJECTIVE: The aim is to examine the association between genetically predicted dairy intake and PD using two-sample Mendelian randomization (MR).
METHODS: We genotyped a well-established instrumental variable for dairy intake located in the lactase gene (rs4988235) within the Courage-PD consortium (23 studies; 9823 patients and 8376 controls of European ancestry).
RESULTS: Based on a dominant model, there was an association between genetic predisposition toward higher dairy intake and PD (odds ratio [OR] per one serving per day = 1.70, 95% confidence interval = 1.12-2.60, P = 0.013) that was restricted to men (OR = 2.50 [1.37-4.56], P = 0.003; P-difference with women = 0.029).
CONCLUSIONS: Using MR, our findings provide further support for a causal relationship between dairy intake and higher PD risk, not biased by confounding or reverse causation. Further studies are needed to elucidate the underlying mechanisms. © 2022 International Parkinson and Movement Disorder Society.
Subject classification (UKÄ)
- Dairy Products/adverse effects
- Genetic Predisposition to Disease/genetics
- Genome-Wide Association Study
- Mendelian Randomization Analysis
- Parkinson Disease/epidemiology
- Polymorphism, Single Nucleotide/genetics
- Risk Factors