Effects of vitamin D on motor symptoms and cognitive functions in people with Parkinson’s disease

Aim of the study: Parkinson’s disease is the second most common neurodegenerative disorder. The present study investigates the role of vitamin D deficiency thought to be one of the etiopathological and modifying factors in Parkinson’s disease that is known to be multifactorial.

Materials and Methods: Designed as a retrospective review of medical records, this study compares the serum vitamin D levels of the idiopathic Parkinson’s disease patients with and without dementia to those of the healthy individuals with no metabolic/degenerative disorders. It also investigates the relationship between the patients’ Standardized Mini-Mental State Examination (SMMSE) and the Unified Parkinson’s Disease Rating Scale (UPDRS) scores and serum vitamin D levels to show the effects of vitamin D on motor symptoms and cognitive functions.

Results: In this study, we compared the serum vitamin D levels of 40 Parkinson’s disease patients and 15 Parkinson’s disease patients with dementia to those of the control group comprising 30 healthy individuals. Vitamin D levels were 21,4±15,9 ng/mL in the control group; 16,5±6,4 ng/mL in Parkinson’s disease patients and 13,8±4,5 ng/mL in Parkinson’s disease patients with dementia. All the patient groups had significantly lower vitamin D levels than the control group (p<0,005). Within the Parkinson’s disease group, furthermore, the dementia group had lower vitamin D levels than the non-dementia group. Having examined the relationship between the SMMSE scores and serum vitamin D levels, we found a significant difference in the Parkinson’s disease dementia group (p: 0,020), as well as a relationship of 59,4% in the same direction. On the other hand, there was no significant difference in either patient group in the scores of UPDRS evaluating clinical disability.

Conclusion: Consistent with the literature, the present study found that people with Parkinson’s disease had lower mean values of serum vitamin D levels than the control group and showed that serum vitamin D levels were correlated with the cognitive performance. However, the study could not find a relationship between the serum vitamin D levels and the motor performance.