Journal of Parkinson's Disease; Volume 3, Number 4 / 2013, Pages 547-555
Amie L. Peterson 1, 5, Charles Murchison 5, Cyrus Zabetian 2, 3, 6, James B. Leverenz 2, 3, 4, 6, G. Stennis Watson 3, 6, Thomas Montine 6, Natasha Carney 1, Gene L. Bowman 5, Karen Edwards 6, Joseph F. Quinn 1, 5
1 Parkinson's Disease Research, Education & Clinical Center (PADRECC), Portland VA Medical Center, Portland, OR, USA
2 Parkinson's Disease Research, Education & Clinical Center (PADRECC), VA Puget Sound Health Care System, Seattle, WA, USA
3 Geriatic Research, Education & Clinical Center (GRECC), VA Puget Sound Health Care System, Seattle, OR, USA
4 Mental Illness Research, Education & Clinical Center (MIRECC), VA Puget Sound Health Care System, Seattle, WA, USA
5 Oregon Health & Science University, Portland, OR, USA
6 University of Washington, Seattle, WA, USA
Background: Research in recent years has suggested a role of vitamin D in the central nervous system. The final converting enzyme and the vitamin D receptor are found throughout the human brain. From animal studies vitamin D appears important in neurodevelopment, up-regulation of neurotrophic factors, stabilization of mitochondrial function, and antioxidation.
Objective: To examine the relationship between serum vitamin D and neuropsychiatric function in persons with Parkinson's disease (PD).
Methods: This is an add-on study to a longitudinal study following neuropsychiatric function in persons with PD. Baseline neuropsychiatric performance and serum 25-hydroxyvitamin D were examined for 286 participants with PD. Measures of global cognitive function (MMSE, MOCA, Mattis Dementia Scale), verbal memory (Hopkins Verbal Learning Test), fluency (animals, vegetables, and FAS words), visuospatial function (Benton Line Orientation), executive function (Trails Making Test and Digit-Symbol Substitution), PD severity (Hoehn & Yahr and Unified Parkinson's Disease Rating Scale) and depression (Geriatric Depression Scale (GDS)) were administered. Multivariate linear regression assessed the association between vitamin D concentration and neuropsychiatric function, in the entire cohort as well as the non-demented and demented subsets.
Results: Using a multivariate model, higher vitamin D concentrations were associated with better performance on numerous neuropsychiatric tests in the non-demented subset of the cohort. Significant associations were specifically found between vitamin D concentration and verbal fluency and verbal memory (t = 4.31, p < 0.001 and t = 3.04, p = 0.0083).
Vitamin D concentrations also correlated with depression scores (t = −3.08, p = 0.0083) in the non-demented subset.
Conclusions: Higher plasma vitamin D is associated with better cognition and better mood in this sample of PD patients without dementia. Determination of causation will require a vitamin D intervention study.
- Vitamin D may prevent cognitive impairment in Parkinson's patients MedNewsToday comment on this study
For all patients, those who had higher levels of vitamin D were better able to recall names and experienced a shorter delay in remembering items on a verbal learning test.
But on dividing the participants into dementia and non-dementia groups, higher levels of vitamin D only appeared to improve fluency and verbal learning for Parkinson's patients who were free of dementia.
They note that higher vitamin D levels had no impact on depression for participants with dementia,