AUTHOR=Luo Xiaoyue , Ou Ruwei , Dutta Rajib , Tian Yuan , Xiong Hai , Shang Huifang 

TITLE=Association Between Serum Vitamin D Levels and Parkinson's Disease: A Systematic Review and Meta-Analysis

JOURNAL=Frontiers in Neurology

VOLUME=9

YEAR=2018

URL=https://www.frontiersin.org/journals/neurology/articles/10.3389/fneur.2018.00909

DOI=10.3389/fneur.2018.00909

ISSN=1664-2295

ABSTRACT=<p><bold>Background:</bold> Vitamin D is an important secosteroid which is involved the development and regulation of brain activity. Several studies have focused on exploring the relationship between serum vitamin D levels and Parkinson's disease (PD), but the conclusion remains ambiguous.</p><p><bold>Methods:</bold> We searched observational studies that explored the association between serum vitamin D levels and PD based on PubMed, EMBASE and Cochrane library from inception through to January 2018. The quality of included studies was evaluated by using Newcastle-Ottawa Scale (NOS). Statistical analysis of this meta-analysis was performed by Stata version 12.0 and R software.</p><p><bold>Results:</bold> Twenty studies with a total of 2,866 PD patients and 2,734 controls were included. Compared with controls, PD patients had lower serum vitamin D levels (WMD −3.96, 95%CI −5.00, −2.92), especially in higher latitude regions (WMD −4.20, 95%CI −5.66, −2.75). Assay methods contributed significantly to high heterogeneity. Furthermore, PD patients with deficient vitamin D levels had advanced risk (OR 2.08, 95%CI 1.35, 3.19) than those patients with insufficient ones (OR = 1.73, 95%CI 1.48, 2.03). In addition, serum vitamin D levels were also related to the severity of PD (WMD −5.27, 95%CI −8.14, −2.39) and the summary correlation coefficient showed strongly negative correlation (<italic>r</italic> = −0.55, 95%CI −0.73, −0.29). Moreover, the pooled correlation coefficient revealed that serum vitamin D levels were also negatively correlated to the Unified Parkinson's Disease Rating Scale III (UPDRS III) (<italic>r</italic> = −0.36, 95%CI −0.53, −0.16), but did not correlate with the duration of PD (<italic>P</italic> = 0.37) and age of patients (<italic>P</italic> = 0.49).</p><p><bold>Conclusion:</bold> Serum vitamin D levels are inversely associated with the risk and severity of PD. Our results provided an updated evidence of association between low vitamin D levels and PD and prompt the adjunctive therapeutic decisions about vitamin D replacement in PD.</p>