Correlation between Hypovitaminosis D and Nutritional Status with The Severity of Clinical Symptoms And Impaired Cognitive Function in Patients with Parkinson's Disease.

Purpose: To evaluate the relationship between the severity of clinical symptoms and cognitive function of patients with Parkinson's disease (PD) and the serum vitamin D level and nutrition status.

Methods: Thirty-three adult PD patient were included in the study (November 2016 to October 2018) and their clinical symptom severity (including the Hoehn and Yahr scale and unified Parkinson's disease rating scale (UPDRS)) and cognitive function (mini-mental state examination) were assessed in two visits (at time of enrollment and one year after the enrollment). In the meanwhile, their renal/liver function, serum level of vitamin D, vitamin B12, Folate and high-sensitive C-reactive protein were also measured for clinical correlation and comparisons.

Results: From the two visits, we found our patients divided into two group, the well-nourished status group and at risk or malnutrition status group. In both visits, we uncovered patients at risk of malnutrition status had worse clinical severity and more impaired memory. As for hypovitaminosis D, the vitamin D level alone made no significant correlation with the clinical severity and cognitive function.

Conclusion: This study revealed that PD patient with at risk of malnutrition status has impaired cognitive function but patients with abnormal serum vitamin D level did not have such influence. But PD patients with abnormal vitamin D level have a higher hs-CRP level which has an influence on the cognitive function of PD patients. Therefore, abnormal serum vitamin D level may have an indirect influence on the cognitive function of PD patients through the influence on the hs-CRP level. This study is limited by the small case-number and short follow-up time. Further large scale study and longer observation period are needed for a better delineation of the relationship between the serum vitamin D level and nutritional status with the clinical condition of the PD patients.