April 27, 2001 -- The inevitable memory problems that accompany old age may not be so inevitable after all. New research suggests that high levels of an amino acid that has been linked to heart disease and stroke may be partially responsible for age-related memory loss.
If these and other findings are confirmed, simple vitamin therapy aimed at reducing levels of the amino acid homocysteine in the blood may prove effective in reducing the risk of numerous age-related diseases and maladies, experts say.
"I predict that in five years, testing homocysteine levels may be as common as testing cholesterol," Donald Jacobsen, PhD, director of the Laboratory for Homocysteine Research at the Cleveland Clinic Foundation, tells WebMD. "We have known about homocysteine's cardiovascular connection for at least 10 years, and studies in the last year or so suggest it plays a role in Alzheimer's disease. You could say homocysteine is an emerging risk factor for [thinking] impairment."s testing cholesterol," Donald Jacobsen, PhD, director of the Laboratory for Homocysteine Research at the Cleveland Clinic Foundation, tells WebMD. "We have known about homocysteine's cardiovascular connection for at least 10 years, and studies in the last year or so suggest it plays a role in Alzheimer's disease. You could say homocysteine is an emerging risk factor for [thinking] impairment."
Reporting in the May issue of the American Journal of Clinical Nutrition, researchers from Boston's Tufts University found that high circulating levels of homocysteine were related to short-term memory problems in a group of men and women over the age of 60 who were tested for [thinking] performance. All of those tested were participating in the third National Health and Nutrition Examination Survey, designed to track the health and nutritional status of Americans.
High homocysteine levels were independently associated with poor performance on the memory tests, as were low levels of the vitamin folic acid. Folic acid, or folate, has been shown to significantly lower homocysteine levels.
"The message here is that folate status is important, but I don't think this means people need to be taking folate supplements," study author Martha Savaria Morris, PhD, of Tuft's Jean Mayer USDA Human Nutrition Research Center of Aging, tells WebMD. "Ever since the late 1990s, our food supply has been fortified with folate. People are getting it in the grains they eat, and that is likely to be enough to get the benefits."
Jacobsen disagrees. He says a cocktail of three vitamin supplements -- folic acid, B12, and B6 -- can dramatically lower homocysteine levels, even in those who get the recommended levels of the vitamins in their diets.
"Homocysteine levels naturally increase as you age," he says. "And anyone who is not supplementing and is eating a regular western diet probably has high-normal to very high homocysteine."
Jacobsen, 62, recommends taking 400-800 mcg of folic acid every day and 25-100 mg of vitamin B6. He says it is not clear if B12 supplementation is beneficial in younger people, but it does appear to benefit those over 50. He takes 500 mcg of B12 each day.
"There is no doubt in my mind that supplementation lowers homocysteine levels," he says. "We live in an age of evidence-based medicine, though, and we don't have the evidence yet to conclusively show that lowering homocysteine has any positive clinical effect. But it is also very safe to take these three water-soluble vitamins."
So should homocysteine levels be checked routinely, just like cholesterol and blood pressure? One problem with this, experts say, is that there is still controversy about what constitutes high and normal homocysteine levels. And the CDC is working to standardize homocysteine measurement. In November of 1999, CDC researchers compared the accuracy of homocysteine assay readings at 14 different labs around the U.S., and found significant discrepancies.
Ongoing studies may prove that lowering homocysteine levels can help prevent memory problems associated with aging, but Morris says it is already clear that other unidentified factors are also involved.
"It is a little discouraging, but it does appear that as you age your memory does decrease," she says. "Hopefully, folate fortification can impact this. But it is still a fact that our short-term memory at age 70 is probably going to be worse than it was at age 60, and we don't really know why."