Vitamin D in the Parkinson Associated Risk Syndrome (PARS) study

Abstract

Background: Lower vitamin D levels have been associated with manifest Parkinson's disease, prompting the hypothesis that vitamin D insufficiency or deficiency may increase risk for PD.

Objectives: To evaluate vitamin D levels in a population at risk for developing PD.

Methods: Plasma vitamin D levels were measured in the Parkinson Associated Risk Syndrome Study, a cohort of asymptomatic individuals, some of whom are at high risk for PD. Vitamin D levels were compared between subjects at high risk for PD (hyposmia and dopamine transporter scan deficit) versus all others and examined for correlations with dopaminergic system integrity.

Results: Mean vitamin D levels did not differ between groups, with a level of 27.8 ng/mL (standard deviation = 12.0) in the high-risk group versus 24.7 ng/mL (standard deviation = 9.0) in all others (P = 0.09). Vitamin D levels did not associate with putaminal dopamine transporter uptake.

Conclusions: Our data from the asymptomatic Parkinson Associated Risk Syndrome cohort do not support the hypothesis that chronic vitamin D insufficiency threatens dopaminergic system integrity, contributing to PD pathogenesis. © 2017 International Parkinson and Movement Disorder Society.

Keywords: Parkinson's disease; cognition; cohort studies; vitamin D.

FIG. 1

Vitamin D levels and status in PARS participants stratified by risk. (A) Swarm plots with box plots of vitamin D levels in the high-risk group (hyposmia + DAT<80%) vs. all others. (B) Swarm plots with box plots of vitamin D levels in the highest-risk group (hyposmia + DAT <65%) vs. all others. (C) Vitamin D deficiency and insufficiency in the high-risk group (hyposmia + DAT <80%) vs. all others. (D) Vitamin D deficiency and insufficiency in the highest-risk group (hyposmia + DAT <65%) vs. all others. Box plots denote median and interquartile range. Vitamin D deficiency is defined as total vitamin D <20 ng/mL, insufficiency as total vitamin D 20 to 30 ng/mL, and sufficiency as total vitamin D >30 ng/mL.