Study Of Vitamin D Levels And Vitamin D Associated Factors In Alzheimer’s Disease And Parkinson’s Disease Patients

Vitamin D is one of the indispensable important vitamins in the body. In the past, it has been found that low vitamin D status is linked to various diseases, including diabetes mellitus, hypertension, multiple sclerosis and cognitive dysfunction. Vitamin D has aroused more and more social attention. In recent years studies of vitamin D and neurodegenerative diseases have aroused more and more social attention, especially Alzheimer’s disease and Parkinson’s disease. In this paper, we study of vitamin D levels or vitamin D associated factors in Alzheimer’s disease or Parkinson’s disease patients. The key findings are as follow:(1) Many studies have reported an association between vitamin D and Alzheimer’s disease (AD) or Parkinson’s disease (PD). Our purpose is to summarize the available information and evaluate the vitamin D levels in AD and PD patients. We searched all publications in English language on the association of vitamin D and AD or PD risk and was performed the pooled analysis by Statal2.0. In total, six articles from including 319 AD cases and 573 controls and five articles from including 434 PD cases and 3451 controls were included in the meta-analysis. It was found that AD patients had lower levels of 25(OH)D than healthy controls (summary standardizedmean difference [SMD]=-1.39; 95% confidence interval [CI]=-2.79 to 0.01). Similar results were found for PD patients versus healthy controls (summary SMD=-1.33; 95%CI=-2.44 to -0.21).(2) It has been demonstrated that vitamin D status is an important factor of skeletal integrity, and inadequate serum 25(OH)D level is associated with muscle weakness and increased incidences of falls and fractures. As we draw a conclusion of both AD and PD patients have lower levels of 25(OH)D than controls, the purpose of the present study is to perform a meta-analysis to explore the association between AD and risk of hip fracture. Considering that bone mineral density (BMD) acts as a strong predictor of bone fracture, we also studied the hip BMD in AD patients. There are 9 studies included in the meta-analysis of AD. The results indicate that AD patients are at higher risk for hip fracture (OR and 95%CI fixed:ES=2.58,95%CI=[2.03,3.14]; dichotomous data:summary OR =1.80,95%CI=[1.54,2.11]) than healthy controls. Further meta-analysis showed that AD patients have a lower hip BMD (summary SMD=-1.12,95%CI=[-1.34,-0.90]) than healthy controls. There are 15 studies included in the meta-analysis of PD. The results indicated that PD patients are at higher risk for osteoporosis (summary OR=1.18,95% CI=[1.09,1.27]) than healthy controls. The gender subgroup analysis suggested that PD male patients have a higher risk for osteoporosis than female patients (female patients: summary OR=1.16,95%CI=[1.07,1.26]; male patients:summary OR=2.44,95% CI=[1.37,4.34]). Further meta-analysis showed that PD patients have a lower hip, lumbar spine and femoral neck BMD than healthy controls.(3) Vitamin D receptor (VDR) is responsible for the formation of the highly active vitamin D metabolite (1,25(OH)2D). We think there is an association between VDR and AD, so the purpose of the present study is to perform a meta-analysis to explore the association between VDR polymorphisms and AD. There are 9 studies included in the meta-analysis. The results indicate that AD cases had a significantly lower frequency of A allele of Apal (OR=0.79,95%CI=0.65-0.96) and T allele of TaqI (OR=0.79,95%CI= 0.65-0.96) among in all study subjects. But no association was found between AD and the VDR FokI F allele among in all study subjects (OR=1.04,95% CI=0.89-1.23). The findings will be of significance to the prevention and treatment of AD.