Serum 25(OH)D as a Biomarker for Cognitive Impairment in Parkinson Disease

In Parkinson disease (PD), cognitive impairment was related to vitamin D, indicating that serum 25(OH)D may be a useful diagnostic marker for impairment. These findings were published in Journal of Clinical Neuroscience.

One of the most important nonmotor symptoms of PD is cognitive impairment. It can occur at any stage of disease and affects quality of life. Recent studies have implicated serum vitamin D in PD progression and in non-PD cognitive impairment. It is, therefore, reasonable to suggest that vitamin D may also play a role in PD cognitive decline.

For this prospective, observational, cross-sectional cohort study, patients (n=112) with PD and healthy control individuals (n=70) were recruited between 2019 and 2021 at the Affiliated Hospital of Xuzhou Medical University in China. Patients underwent a cognitive examination; patients and controls were evaluated for serum 25(OH)D levels.

The PD and control groups were aged mean 65.0±8.0 and 66.7±8.7 years, the men:women ratios were 69:43 and 38:32, and they reported 3.98±1.19 and 4.08±1.25 hours of sunlight exposure per day, respectively.

The PD group had lower serum 25(OH)D levels (mean, 45.86 nmol/L) than individuals in the control group (mean, 56.54 nmol/L; P <.001).

Among the PD group, 37 had normal cognition, 51 had mild cognitive impairment, and 24 had dementia. More women had impaired cognition or dementia (P =.028) and those with dementia had fewer years of education (P =.002). Montreal cognitive assessment (MoCA) scores (P <.001) and serum 25(OH)D levels (P <.001) were lowest in dementia and highest in normal cognition.

After adjusting for confounders, serum 25(OH)D was significantly correlated with MoCA scores (r, 0.358; P <.001).

In a binary logistic regression, serum 25(OH)D predicted risk for incident cognitive impairment in PD (β, -0.052; P =.005) after adjusted for age, gender, BMI, education, disease duration, and sun exposure. A serum 25(OH)D cutoff of 40.75 nmol/L had an area under the curve (AUC) of 0.713, sensitivity of 53.3%, and specificity of 86.5% for predicting cognitive impairment in PD.

This study was limited by its cross-sectional design, in which it remains unclear whether there is a causal relationship between cognition and vitamin D in PD.

This study suggested that “serum 25(OH)D may be a useful biomarker for diagnosing cognitive impairment in patients with PD,” the researchers concluded. Additional studies are needed to determine the clinical utility of vitamin D in the setting of PD.

Reference

Wu H, Raza HK, Li Z, et al. Correlation between serum 25(OH)D and cognitive impairment in Parkinson’s disease. J Clin Neurosci. 2022;100:192-195. doi:10.1016/j.jocn.2022.04.015