April 28, 2003

Evidence Links “Silent” Strokes to Alzheimer’s

Adopting the heart-healthy measures long advocated to prevent heart attacks and strokes might be a good hedge against memory decline, new research suggests. Dutch researchers report that symptom-free, unnoticed strokes in the brain may double your risk for developing the mind-robbing ravages of Alzheimer’s disease Sometimes called “brain attacks,” strokes most commonly result from the same artery-clogging damage that leads to heart attacks.

With a stroke, hardening of the arteries occurs in the blood vessels feeding the brain; with a heart attack, blood supply to the heart is blocked. Keeping the blood vessels open and healthy through diet, exercise, and regular medical care may help to guard against both life-threatening events. This study was the first major one to look at “silent” strokes. Unlike regular strokes, which cause weakness in an arm or leg or difficulty speaking, these “silent” strokes are small and go unnoticed. They can occur in healthy older people and, over the course of years, lead to gradual mental decline.

What the Study Found

This large trial, from the Erasmus Medical Center in the Netherlands and published in the March 27, 2003 issue of the esteemed New England Journal of Medicine, adds to the growing body of evidence that circulatory problems in the brain contribute to the development of Alzheimer’s disease. The study looked at more than 1,000 healthy older men and women aged 60 through 90. All were free of memory deficits, earlier strokes, or other major medical problems.

The participants underwent a sophisticated computer imaging technique called MRI that scanned their brains to look for problems like poor blood flow and signs of brain damage. They were also given extensive memory tests to look for signs of mental and cognitive decline. The more than 700 volunteers who completed the study then had another MRI scan and battery of tests three to four years later. At the end of the study, 26 of the men and women had developed Alzheimer’s, and four had other forms of dementia.

Those study participants who had evidence of “silent” strokes were more than twice as likely to develop dementia. The study confirms earlier links between poor circulation, strokes, and Alzheimer’s disease, although the relationship remains uncertain. For example, some people with Alzheimer’s show no signs of hardening of the arteries or “silent” strokes. In addition, “silent” or even full-blown strokes can strike many older people who remain clear thinking and alert. More commonly, however, people with Alzheimer’s do show evidence of blocked blood vessels, particularly in the arteries that feed the brain.

What’s more, if you’ve had a stroke in the past, you are at increased of developing Alzheimer’s down the road. The researchers also speculate that “silent” strokes may speed mental decline in those whose brains are already diseased by Alzheimer’s.

Cutting Your Risk

Going out to get tested for “silent” strokes is not something that’s routinely done. Whether a stroke is “silent” or not depends on many factors, including how large an area of the brain is affected, where in the brain it occurs, whether you are asleep or awake when it strikes, and even whether friends, family, or you yourself notice any problems. MRI is costly and not ordinarily recommended to diagnose “silent” strokes. A better step is to adopt lifestyle and medical measures to prevent strokes in the first place. What’s good for the heart, this and other research continues to confirm, is also good for the brain.

Among the measures experts recommend:

*If you’re overweight, drop some pounds.

*If you smoke, quit.

*Get regular medical checkups. If you develop high blood pressure or high cholesterol, get treated for it.

*If you drink alcohol, limit yourself to one to two drinks a day.

*Exercise regularly. Check with your physician about a routine that’s right for you.

*Eat a diet rich in fruits and vegetables and low in artery-clogging fats.

*Ask your doctor if “an aspirin a day” is right for you. Aspirin and other drugs can limit your chance of having a stroke.

*Ward off “the blues.” Many of those who fret about declining memory are actually depressed and can be treated with appropriate medicines. Antidepressants can also foster improvements in those with Alzheimer’s.

By Toby Bilanow, Medical Writer, for www.ALZinfo.org. Reviewed by Samuel E. Gandy, M.D., Ph.D., Chairman of the Scientific Advisory Board, Fisher Center for Alzheimer’s Research Foundation.