A systematic review and meta-analysis published in the Journal of Alzheimer’s Disease reports that Alzheimer’s disease (AD) patients have low serum vitamin D concentrations, when compared with matched controls.
Dr Cedric Annweiler and colleagues selected 10 studies to be included in the review. Data was collected from case-control studies, cross-sectional analysis, and prospective longitudinal studies. The participants were between 66-81 years. Controls were age and gender matched, cognitively normal community-dwellers. The authors report:
- Six of the nine case-control studies found significant differences in serum vitamin D concentrations in Alzheimer Disease participants when compared with controls.
- One study found a decreasing trend of 25(OH)D concentration among those with mild AD when compared with controls.
- Vitamin D insufficiency (≤20 ng/mL) was associated with AD after adjusting for potential confounders.
- The single longitudinal prospective study found no association between 25(OH)D status and participants who did and did not develop AD during a 7-year follow up.
The meta-analysis performed included 7 case-control studies with a total of 357 cases and 648 controls. The authors report a clinically significant association of low vitamin D status with AD. They explain:
“…the probability is about 140%that an individual without AD would have higher serum 25OHD concentration than an individual with AD if both individuals were chosen at random from a population.”
The researcher’s note that the research provides evidence that vitamin D could be a potential biomarker of AD.
They hypothesize that low vitamin D status may contribute to an increased susceptibility to AD; however, more research is needed to understand the full involvement of vitamin D in AD. They conclude:
“It should yet be noted that, even though most aged people have a low vitamin D concentration, all might not get AD. It is thus unlikely that low vitamin D concentration explains the onset of AD by itself. Conversely, it can be assumed that age-related hypovitaminosis D weakens the central nervous system and makes it more sensitive/less responsive to any stress resulting in or enhancing AD pathogenesis and progression…”