HELSINKI, Finland—Higher vitamin D levels may protect against development of Parkinson’s disease, according to findings from a new cohort study (Arch Neurol. 2010;67(7):808-11. DOI: 10.1001/archneurol.2010.120). In an introduction to the study, Paul Knekt, DPH, and colleagues from Finland’s National Institute for Health and Welfare noted the risk factors for Parkinson’s disease are relatively unknown. However, they suspect vitamin D may play a role, as continuously inadequate vitamin D status could lead to a chronic loss of dopaminergic neurons.
In the current trial, the researchers from used data from the Mini-Finland Health Survey, conducted from 1978 to 1980, with follow-up through the end of 2007. The team determined levels of serum 25-hydroxyvitamin D (25[OH]D), a marker of vitamin D status, from frozen samples stored at baseline, and compared to incidence of Parkinson’s disease in 3,173 older adults; 50 incident Parkinson’s disease cases were reported.
Individuals with 25(OH)D concentrations of at least 50 nmol/L had a 65 percent lower risk of developing Parkinson’s compared to subjects with levels less than 25 nmol/L, after adjustment for several potential confounders including sex, education, smoking and body mass index. Further, the researchers did see a dose-response relationship, despite the population’s overall low vitamin D levels. However, they did add the small number of cases, inability to take into account seasonal variation in 25(OH)D levels and limited information on dietary intake of vitamin D raise the possibility of confounding, making further large cohort studies needed.
An accompanying editorial in the same issue of Archives of Neurology (2010;67(7):795-97) called the study “an important logical progression” from previous work on vitamin D and Parkinson’s disease, which should provide data to guide the development of future intervention trials. The author, Marian Leslie Evatt, M.D., Emory University, Atlanta, noted there is a solid body of basic research which “lends plausibility to a role for adequate vitamin D status protecting against development of [Parkinson’s disease],” although further research is needed to determine the role of vitamin D, mechanism of action and optimal dosage.
