B Vitamins No Help for Alzheimer's
Alzheimer's Patients Decline Despite High-Dose Folate, Vitamin B6/B12
B Vitamins, Homocysteine, and Alzheimer's
Folate (a form of vitamin B9), vitamin B6, and vitamin B12 reduce levels of homocysteine in the body. People with Alzheimer's disease tend to have high homocysteine levels. Moreover, evidence suggests that homocysteine makes the main ingredient in brain-clogging plaque -- amyloid -- more toxic.
There's no doubt that B vitamins lower homocysteine. In the Aisen study, Alzheimer's patients who took folate (5 milligrams/day), vitamin B6 (25 milligrams/day), and vitamin B12 (1 milligrams/day) had 31% lower homocysteine levels than patients taking placebo.
But that didn't seem to help -- at least among patients with no underlying vitamin deficiency.
"We were successful in lowering homocysteine, but it had absolutely no effect on the clinical symptoms of Alzheimer's disease," Aisen says.
Shao notes that patients in the Aisen study did not have particularly high homocysteine levels to begin with. He says the study has not answered the question of whether Alzheimer's patients with extremely high homocysteine levels might benefit from high-dose B vitamins.
It's time to move on, says Aisen, who serves as director of the Alzheimer's Disease Cooperative Study (ADCS) that investigates potential new Alzheimer's treatments.
"I think this study is the end of the treatment of Alzheimer's disease with these vitamins," he says.
The Aisen study, and an editorial by Clarke and colleague Derrick A. Bennett, PhD, appear in the Oct. 15 issue of TheJournal of the American Medical Association.