Alzheimer's Disease - Input of Vitamin D With mEmantine Assay

Memantine is administered to all participants according to the usual strategy, with upward titration of 5 mg per week during the first three weeks to reduce the risk of side effects. The final dosage is 20 mg per day, with no subsequent modification of dosage or specialty during the trial.

Subjects receive Vitamin D supplementation (cholecalciferol 100,000 IU, drinking solution, 2 mL vial) at a rate of 1 drinking vial of 100,000 IU cholecalciferol every month. In brief, the total dose is 600,000 IU over the duration of the study starting with one vial at the time of inclusion, then at week(W) 4, W8, W12, W16 and W20. The dose of vitamin D supplementation will not be adjusted except in case of an adverse event such as hypercalcemia. In this case, vitamin D supplementation is stopped and the participant is released prematurely from the study.

Subjects receive Vitamin D placebo (drinking solution, 2mL vial) at a rate of 1 drinking vial every month. In brief, the subjects start with one vial at the time of inclusion, then at week(W)4, W8, W12, W16 and W20. The placebo drinking solution contains all the excipients present in the Vitamin D vial.