New evidence of an association between elevated homocysteine levels in the blood and increased risk of cognitive dysfunction, including dementia and Alzheimer’s disease, has been demonstrated in a recent prospective study. Researchers at Boston University and Tufts University in Massachusetts, with support from the National Institute on Aging, found increased homocysteine to be a strong and independent risk factor for the development of these conditions. The findings are significant because homocysteine levels in the blood can be reduced by increasing the intake of folic acid and the vitamins B12 and B6, a method of prevention now being explored.

The study included 1,092 older individuals from the famous Framingham Study in Massachusetts who did not have dementia at the beginning of the study. Records of their plasma homocysteine were assessed between 1986 and 1990. The participants were then followed for an additional 8 years, on average. By the end of this period, dementia had developed in 111, including 83 with Alzheimer’s disease. The findings demonstrated that homocysteine levels above 14 umol/L doubled the risk of developing these cognitive disorders and each additional increase of 5 umol/L raised the risk by 40%.

While the good news is that this relationship between homocysteine, an amino acid also associated with risk of heart attack and stroke, and conditions of memory impairment, such as dementia and Alzheimer’s disease, has been established, continued research is needed to determine whether reducing homocysteine, such as with folate and B12 and B6 vitamin supplements and diets rich in these substances, will reduce this risk. Clinical trials are being planned now to test this hypothesis.