A randomized controlled trial of high-dose vitamin D2 followed by intranasal insulin in Alzheimer's disease.

Poor vitamin D nutrition is linked with dementia, but vitamin D has not been tested in a randomized controlled trial (RCT) in Alzheimer's disease (AD). Nasal insulin acutely improves cognition and vitamin D upregulates insulin receptor expression and enhances insulin action. In an RCT we examined the effect of high-dose vitamin D followed by nasal insulin on memory and disability in mild-moderate AD.