A good heart could be the key to a good mind

A healthy circulatory system may play a big role in keeping the aging mind sharp, according to a new wave of research.

BY JACOB GOLDSTEIN

jgoldstein@herald.com

Blood feeds the brain.

It feeds the whole body, of course, with the nutrients and oxygen that give cells energy. But the brain is especially demanding -- a three-pound lump that consumes one-fifth of the body's energy supply.

It has long been clear that cardiovascular catastrophes can have a profound impact on the brain. When a patient's heart stops beating, the brain is among the first organs to suffer irreparable damage. Strokes -- which occur when a clot blocks the flow of blood to the brain, or when an artery in the brain bursts -- often leave victims disabled or dead.

In recent years, though, a new wave of research has suggested the relationship between blood flow and the brain goes deeper. The mind's ability to deal quickly with complex tasks declines naturally with age. But a stressed cardiovascular system may accelerate the process, experts say.

And, while cardiovascular problems alone do not cause Alzheimer's Disease, they may be one of the key triggers that can allow Alzheimer's to take hold.

Put another way: Taking care of the heart as you age may help protect the mind.

''We used to think there was cardiovascular disease and then there was cognition,'' says Dr. Ranjan Duara, medical director of Mount Sinai's Wien Center for Memory Disorders. ``There's more and more evidence that one feeds the other.''

Many of the risk factors that affect cardiovascular health -- high blood pressure, high cholesterol, genetic factors, diabetes -- also seem to affect brain health, says Carl W. Cotman, director of the Institute for Brain Aging at the University of California, Irvine. Conversely, taking care of the cardiovascular system also seems to be good for the mind.

''Exercise, which has been well known for generations to reduce the risk of heart disease, now has recently been described to delay the onset of Alzheimer's Disease,'' he says. ``It's quite striking.''

The relationship between blood flow and cognitive health is still poorly understood, and is likely the result of multiple factors interacting with each other. Dr. Kenneth Langa of the University of Michigan's Institute of Gerontology explains one possible model:

High blood pressure and high cholesterol damage the lining of the small blood vessels in the brain, reducing blood flow and depriving nearby brain cells of nutrients. ''This trouble in blood flow to parts of the brain [may be] doing damage and shifting people down the cognitive decline curve,'' he says.

As evidence of this hypothesis, Langa cites brain scans of elderly people, which often reveal lesions in the white matter near the center of the brain. High blood pressure and high cholesterol may contribute to the development of the lesions -- and the extent of the lesions may be correlated with cognitive decline, Langa says.

It's unclear just how important cardiovascular processes are both in normal mental decline and in the onset of dementia -- the debilitating cognitive decline such as that seen in Alzheimer's patients.

''It's still debated how much is actually vascular disease and how much is Alzheimer's,'' says Dr. Kristine Yaffe of the University of California at San Francisco's memory and aging center.

Many studies have showed correlations between cardiovascular risk factors and Alzheimer's, but none has clearly shown that cardiovascular problems actually cause the disease.

''We're probably ready to have some trials in which you identify some people at high risk for cardiovascular disease,'' Yaffe says. ``It would be interesting to see -- if you [control] their cardiovascular disease, would you prevent dementia?''