<qa>  What can be reduced by administration of high dose supplements of folate and vitamins B6 and BBlood levels of homocysteine are elevated in Alzheimers disease AD, and hyperhomocysteinemia may contribute to disease pathophysiology by vascular and direct neurotoxic mechanisms. Homocysteine levels can be reduced by administration of high dose supplements of folate folic acid and vitamins B6 and B12. The proposed study is for a multicenter, randomized, controlled clinical trial to determine whether reduction of homocysteine levels with high-dose folateB6B12 supplementation will slow the rate of cognitive decline in subjects with AD. 