Observational studies show a correlation between low vitamin D levels and dementia risk, but this association may be confounded by other health factors.

“I mean there are many many many what are called observational studies that are looking at a correlation between low vitamin D levels and dementia risk. Many different studies have found this same association. And so one might say, well, people that are vitamin D deficient might just be less healthy. They might be going out in the sun less. They're exercising less. And so vitamin D deficiency might just be biomarking some other health factor. So that is a I would say pretty relevant argument.”