The role of Vitamin D levels on neuropsychological profile of patients with Parkinson’s Disease

even on the risk of disease development or disease progression. Only one cross-sectional study in PD patients investigated the role of vitamin D levels on neuropsychiatric functions and found that higher plasma vitamin D is associated with better cognition and better mood in PD patients without dementia. Objective: This prospective longitudinal study was performed to investigate whether low vitamin D levels at baseline are predictors of poor cognitive performances and more severe apathy and depressive symptomatology in PD patients after two years. Material and method: A sample of 48 untreated, drug-naïve PD patients was enrolled in the study. At baseline (T0), serum 25-hydroxyvitamin D and severity of motor symptoms were examined. Moreover, neuropsychological profile was assessed by cognitive tests assessing long-term memory, executive functions, visuospatial functions; Hospital Anxiety and Depression Scale (HADS) and Apathy Evaluation Scale (AES) to assess severity of depressive symptomatology and apathy. After two years (T1), 40 PD patients were evaluated and underwent the same neuropsychological battery administrated at T0. Results: At baseline, low vitamin D levels correlated significantly with poor cognitive performance on verbal immediate and delayed recall tasks, phonological fluency task, semantic fluency task, and with high score on HADS and AES. Linear regression analysis showed that low vitamin D levels contribute to poor performance on cognitive tasks assessing long-term memory, semantic fluency and high score on HADS and AES. Moreover, we found that low vitamin D level recorded at T0 correlated significantly with poor performance on immediate verbal recall, semantic fluency task, interference task of Stroop Test, and with high level of cognitive apathy evaluated at follow-up. Linear regression analysis showed that low vitamin D levels were associated significantly with poor scores on cognitive tasks assessing long-term memory, semantic fluency and with high level of cognitive apathy. Conclusions: Lower level of plasmatic vitamin D at baseline is associated with higher apathy and worse performance on cognitive tests assessing mainly frontal/executive functions at both baseline and follow-up assessment in PD. Therefore, our findings suggested that lower vitamin D levels may be a biomarker of dysexecutive syndrome in early PD patients.