For patients with mild- to moderate- Alzheimer’s disease, cognitive decline was not slowed by the administration of high-dose vitamin B supplementation in an article released on October 14, 2008 in JAMA.

Alzheimer’s Disease (AD) is a degenerative neurological disease that is a common form of dementia. There has been evidence that an amino acid naturally produced in the body, homocysteine, is present in higher levels in cases of Alzheimer’s patients, and homocysteine’s relationship to various neuropathological mechanisms suggests that reducing its levels may alter the course of the disease. According to the authors, B vitamins that influence metabolism of homocysteine have been considered to this end, but previous studies have not yet had sufficient size or duration of follow-up to actually assess their effects on this cognitive disorder.

To investigate the potential of B vitamins in Alzheimer’s treatment, Paul S. Aisen, M.D., of the University of California, San Diego, and colleagues, examined 409 individuals in a randomized controlled trial. One group was supplemented with folic acid (5 mg/d of folate,) vitamin B6 (25 mg/d of vitamin B6,) and vitamin B12 (1 mg/d of vitamin B12) for 18 months. The second group was treated with a placebo. The patients were medicated throughout the study and were tested for their cognitive abilities using the Alzheimer Disease Assessment Scale (ADAS-cog).

It was found that the vitamin supplement was linked to a reduction in homocysteine levels in the blood plasma. however, when examined in light of cognitive testing, ADAS-cog scores did not differ significantly between the two treatment groups. Notably, depression symptoms were more common in the supplemented group.

The authors conclude that, while homocysteine levels dropped in the supplemented patients, but this did not improve cognitive outcomes: “Many studies suggest that relative elevation of homocysteine is characteristic of AD, and laboratory research implicates homocysteine in neurodegenerative mechanisms. High-dose B vitamin supplementation in individuals with normal levels of B vitamins was effective in reducing homocysteine levels. However, our study does not support the treatment of individuals with mild to moderate AD and normal vitamin levels with B vitamin supplements.”

High-Dose B Vitamin Supplementation and Cognitive Decline in Alzheimer Disease: A Randomized Controlled Trial
Paul S. Aisen; Lon S. Schneider; Mary Sano; Ramon Diaz-Arrastia; Christopher H. van Dyck; Myron F. Weiner; Teodoro Bottiglieri; Shelia Jin; Karen T. Stokes; Ronald G. Thomas; Leon J. Thal; for the Alzheimer Disease Cooperative Study
JAMA. 2008;300(15):1774-1783.
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Written by Anna Sophia McKenney