Blood levels of a chemical compound called homocysteine may be increased in Alzheimer disease, and studies have shown that homocysteine levels can be reduced by administration of high-dose supplements of folate and vitamin B. However, high-dose vitamin B supplementation does not seem to slow down cognitive decline in adults with mild to moderate Alzheimer disease, according to a new study published in the Journal of the American Medical Association.

Researchers from the University of California, San Diego and their colleagues studied the efficacy and safety of vitamin B supplementation in 409 individuals with mild to moderate Alzheimer disease and normal folate, vitamin B12., and homocysteine levels at baseline. Approximately 60% of these individuals were treated with high-dose supplements of folate, vitamin B6, and vitamin B12. The remaining 40% were treated with a placebo pill containing no vitamins. Only 340 participants completed the 18-month trial. The researchers found that, although vitamin supplementation was effective in reducing homocysteine levels, it did not have a beneficial effect on cognition, as measured by the Alzheimer Disease Assessment Scale.

Interestingly, those individuals who were treated with high-dose vitamin supplementation were also more likely to experience adverse events involving depression. Although the reason for this is not clear, it seems that, for now, there is no need to provide folate and vitamin B supplementation to patients with mild to moderate Alzheimer disease.