Memory, Mood, and Vitamin D in Persons with Parkinson's Disease

Abstract

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 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.

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“…Further, Peterson et al concluded that, among PD patients without significant dementia, stronger performances on neuropsychiatric tests were associated with higher 25(OH)D 3 levels in the blood. This was especially true for verbal fluency and verbal memory [12]. This group also concluded that vitamin D may play a role in reducing depression [12].…”

“…This was especially true for verbal fluency and verbal memory [12]. This group also concluded that vitamin D may play a role in reducing depression [12]. Utilizing vitamin D to improve bone health, reduce the risk of serious injury from falls, improve cognition and memory, and improve mood may lead to increased quality of life and slowed disease progression for PD patients.…”

“…It has also been suggested that neurological/degenerative, motor, and cognitive issues are impacted by vitamin D, with lower levels potentially increasing the risk and adverse effects of these disorders [8][9][10][11][12]. One such condition that may be impacted by vitamin D levels is Parkinson's disease (PD).…”

“…Beyond its potential antiviral properties, vitamin D may play a role in PD development and progression. Several studies have suggested that patients with PD, especially earlier stage PD, have lower baseline levels of 25(OH)D 3 than healthy controls, and that lower levels of 25(OH)D 3 correspond with an increased disease prevalence and severity [11,12,38]. It is unclear if or why vitamin D, or its lack thereof, may play a role in PD development and progression, but some have noted that VDRs are located on dopaminergic neurons in the substantia nigra, an area degenerated in PD [11,38].…”

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“…Several studies with PD patients have associated vitamin D insufficiency, or variations in the vitamin D receptor, with an increased risk of developing PD (Butler et al, 2011; Evatt et al, 2008; Newmark and Newmark, 2007; Peterson, 2014); and lower levels of vitamin D have also been associated with non-motor symptoms of PD (Jang et al, 2015a; Kwon et al, 2016; Peterson et al, 2013), suggesting a possible link between vitamin D levels and PD. Additionally, a published vitamin D intervention study has demonstrated positive effects of vitamin D supplementation on clinical rating scales in PD patients (Suzuki et al, 2013), providing clinical evidence for a potential therapeutic role for vitamin D or calcitriol.…”