Dairy Intake and Parkinson's Disease: A Mendelian Randomization Study
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Abstract
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. (c)
2022 International Parkinson and Movement Disorder Societ