Relationship between 25-Hydroxyvitamin D, bone density, and Parkinson's disease symptoms.

OBJECTIVES: Vitamin D deficiency is widespread in patients with Parkinson's disease (PD). Our aim was to determine whether serum vitamin D levels correlated with bone mineral density (BMD) and non-motor symptoms in patients with PD. MATERIALS & METHODS: A consecutive series of 182 patients with PD and 185 healthy controls were included. Serum 25-hydroxyvitamin D (25[OH]D) levels were measured by immunoassay, while BMD of the lumbar spine and femoral neck was measured by dual-energy X-ray absorptiometry. Associations between serum vitamin D levels and clinical data were evaluated using partial correlation analysis. RESULTS: Patients with PD had significantly lower serum 25(OH)D levels relative to healthy controls (49.75 ± 14.11 vs 43.40 ± 16.51, P < 0.001). Furthermore, PD patients with lower vitamin D levels had a significantly higher frequency of falls (P = 0.033) and insomnia (P = 0.015). They also had significantly higher scores for the Pittsburgh Sleep Quality Index (PSQI; P = 0.014), depression (P = 0.020), and anxiety (P = 0.009). Finally, patients with PD also had a significantly lower mean BMD of the lumbar spine (P = 0.011) and femoral neck (P < 0.001). After adjusting for age, sex, and body mass index, vitamin D levels significantly correlated with falls, insomnia, and scores for the PSQI, depression, and anxiety. CONCLUSIONS: In patients with PD, vitamin D levels significantly correlated with falls and some non-motor symptoms. However, no associations were found between BMD and the serum 25(OH)D levels in patients with PD. Thus, vitamin D supplementation is a potential therapeutic for non-motor PD symptoms.