Vitamins such as vitamin E, vitamin C and vitamin B12 may help people lower their risk of developing Alzheimer's disease

http://orthomolecular.org/resources/omns/v04n25.shtml

The US Alzheimer's Association's Dr. Ralph Nixon has said that previous research has suggested that vitamins such as vitamin E, vitamin C and vitamin B12 may help people lower their risk of developing Alzheimer's disease. At their website (although you have to search for it), the Alzheimer's Association says, "Vitamins may be helpful. There is some indication that vitamins, such as vitamin E, or vitamins E and C together, vitamin B12 and folate may be important in lowering your risk of developing Alzheimer's. . . One large federally funded study (10) showed that vitamin E slightly delayed loss of ability to carry out daily activities and placement in residential care."