Low vitamin D linked to severe Parkinson's disease, finds study
Italy: Low levels of vitamin D negatively affect the progression of Parkinson's disease (PD), according to a recent study in the journal Nutritional Neuroscience. The study found serum 25(OH)D to be negatively correlated with symptom and disease severity, as well as with cognitive functions.
Patients with parkinson's disease have lower 25-hydroxyvitamin D (25(OH)D) serum levels than the general population. Previous studies have suggested a negative association between 25(OH)D and clinical features of PD, but the data are not consistent. To fill this knowldge gap, Michela Barichella, Fondazione Grigioni per il Morbo di Parkinson, Milano, Italy, and colleagues conducted a cross-sectional, observational study.
The researchers studied serum 25(OH)D, disease (Hoehn-Yahr stage [HY]) and clinical symptom (Unified Parkinson Disease Rating Scale [UPDRS]) severity and global cognitive functions (Mini-Mental State Examination [MMSE]) in 500 consecutive PD patients not using vitamin D supplements. They also collected information on sunlight exposure and dietary intakes (using a 66-item food frequency questionnaire). A convenient sample of age and sex-matched community healthy controls (N = 100) was included as a control group.
Key findings of the study include:
- PD patients had lower 25(OH)D serum levels than controls. Deficiency status (<20 ng/mL) was found in 65.6% of patients.
- 25(OH)D levels were independently correlated to sunlight exposure and vitamin D intake.
- In multivariate models, using a Mendelian randomization approach, lower serum 25(OH)D was associated with more severe disease, worse clinical symptoms (UPDRS Part-III total score and dopaminergic and non-dopaminergic subscores) and greater global cognitive function impairment.
- Neither cognitive functions nor clinical features were associated with reduced intake of vitamin D and sunlight exposure.
"Our study adds to the evidence that low 25(OH)D may affect the progression of PD negatively. Intervention studies in this area are required," concluded the authors.
The study, "Clinical correlates of serum 25-hydroxyvitamin D in Parkinson's disease," is published in the journal Nutritional Neuroscience.