A small study by UC Riverside and the Human BioMolecular Research Center have showed in a phase-I study that when combining Vitamin- D3 with Curcumin (Tumeric) they stimulate certain macrophages in the brain to remove the Amyloid Plaques that are thought to cause Alzheimer's disease.
They showed that Curcumin allowed stronger binding sites for the Macrophages to the Amyloid Beta and that the Vit-D made the Macrophages more robust in eating it.
Vitamin D, Curcumin May Help Clear Amyloid Plaques Found In Alzheimer's Disease - Science Daily