Archief Roodbont

Homocysteine elevation is associated with endothelial and vascular dysfunction, neurotoxicity, and high plasma amyloid levels. Previous short-term clinical trials of dietary B vitamin supplementation to lower homocysteine levels in people with normal or impaired cognitive function have yielded mixed results. In this multisite U.S. study, 409 adults (mean age, 76) with mild-to-moderate Alzheimer disease were randomized to daily supplementation with a combination of folate (5 mg), vitamin B₆ (25 mg), and vitamin B₁₂ (1 mg) or to a daily placebo tablet.

At 18 months, 344 participants had completed the trial; homocysteine levels were significantly lower in the treatment group, but progression of dementia did not differ between groups. No differences were observed in a wide range of standardized assessments of cognitive function and activities of daily living. No overall difference was observed between the two groups in adverse events, although the treatment group evidenced significantly more depression and depressive symptoms (28% vs. 18%).

Comment: These results are consistent with those of a previous meta-analysis (Arch Intern Med 2007; 167:21). Despite the known association of elevated homocysteine levels with progression of dementia, B vitamin supplementation does not attenuate the rate of decline in cognitive function in dementia patients and cannot be recommended. Editorialists note that, once dementia becomes evident, supplementation might be ineffective. Folate supplementation in food has lowered homocysteine levels in the general U.S. population; however, for the rare patient with a very high homocysteine level (i.e., >20 µmol/L), a benefit from B vitamin supplementation remains possible.

— Thomas L. Schwenk, MD

Published in Journal Watch General Medicine October 21, 2008