Increased Homocysteine Levels May Lead to Dementia, Alzheimer's

Increased Homocysteine Levels May Lead to Dementia, Alzheimer's

BOSTON--Increased plasma homocysteine levels are a strong, independent risk factor for the development of dementia and Alzheimer's, according to a new review of the Framingham Study printed in the Feb. 14 issue of the New England Journal of Medicine (346:476-83, 2002) (www.nejm.org). Philip World, M.D., and colleagues from Boston University School of Medicine reviewed 1,092 subject histories from the Framingham Study for a relationship between plasma total homocysteine levels and risk of dementia and Alzheimer's disease. Over a median follow-up period of eight years, 111 subjects developed dementia, with 83 of those cases attributable to Alzheimer's disease. Researchers found that people with consistently high levels of homocysteine throughout the study period were at the highest risk for developing Alzheimer's. Specifically, elevated homocysteine levels (greater than 14 µmol/L) nearly doubled a subject's risk for developing Alzheimer's, and with each 5 µmol/L increase in plasmahomocysteine, the risk of Alzheimer's increased by 40 percent.

"The Framingham population gave us the perfect opportunity to look at homocysteine levels in a group of people without memory problems over a period of several years, well before any evidence of dementia," Wolf said. "This is the clearest demonstration yet of the relationship between elevated homocysteine levels and dementia."

The relationship between Alzheimer's and homocysteine is of particular interest, according to the National Institute on Aging (NIA), a department of the National Institutes of Health (NIH), because blood levels of homocysteine can be reduced by increasing B vitamin intake--folic acid, vitamin B6 and vitamin B12. "Although there is no evidence that actually reducing homocysteine levels will prevent [Alzheimer's] or cardiovascular disease, a healthy diet low in fat and rich in nutrients is always a good idea," Wolf said.

Neil Buckholtz, Ph.D., chief of the Dementias of Aging program at NIA, added, "The evidence is beginning to mount regarding homocysteine's role in dementia. ... We don't know yet whether reducing homocysteine levels will reduce dementia risk, but this is something that can and will be tested in clinical trials."

The Framingham study was supported by NIA, as well as NIH's National Institute of Neurological Disorders and Stroke. The Framingham study was also supported by NIH's National Heart, Lung and Blood Institute.