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Homocysteine -- Risk Factor for Alzheimer's Disease?

High serum levels of homocysteine may signal increased risk for developing vascular dementia or Alzheimer's disease.

Results of recent studies suggest that patients with cardiovascular risk factors have an increased incidence of Alzheimer's disease (AD). This observation raises the question of whether plasma homocysteine -- a recently identified cardiovascular risk factor -- also might be a risk factor for dementia and AD.

Boston researchers identified 1092 participants (mean age, 77 years) from the Framingham Study who were free of dementia; plasma homocysteine levels were determined at baseline. During a median follow-up of 8 years, 111 subjects were diagnosed with dementia (of whom 83 were diagnosed with AD). Risks for any dementia and for AD increased with increasing homocysteine levels. For example, subjects with homocysteine levels higher than 14 µM had about a 2-fold increase in risk for any dementia or AD, compared with subjects who had lower homocysteine levels. Analyses were adjusted for age and other potentially confounding variables.

Comment: These findings raise the intriguing possibility that a potentially modifiable risk factor, hyperhomocysteinemia, promotes the development or progression of Alzheimer's disease. The logical next question is to determine whether some cases of AD could be prevented by dietary supplementation with B vitamins or folate, which reduce plasma levels of homocysteine. One caveat is that nearly all subjects in this study were white.

— Allan S. Brett, MD

Published in Journal Watch General Medicine March 8, 2002

Citation(s):

Seshadri S et al. Plasma homocysteine as a risk factor for dementia and Alzheimer's disease. N Engl J Med 2002 Feb 14; 346:476-83.

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