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'Silent' Stroke Doubles Risk of Dementia

Take Care of Your Blood Vessels to Avoid Losing Mental Function, Expert Says
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March 26, 2003 -- Alzheimer's disease and other forms of dementia may be more than twice as likely to occur in people who have had "silent" brain infarcts -- a stroke that causes no apparent symptoms and afflicts as many as 11 million Americans each year.

This finding, by Danish researchers and published in the March 27 issue of TheNew England Journal of Medicine, is the latest to suggest an increased risk of dementia later and a more severe and rapid decline in memory loss from the brain damage caused by silent strokes.

"I was surprised, when we did the study, to see how large a proportion of elderly people do have small infarcts in their brain that were never clinically recognized," lead researcher Monique M.B. Breteler, MD, PhD, tells WebMD. "One in five people over the age of 60 had at least one silent brain infarct. I was also impressed by the size of the risk increase, which suggests that we should advocate stronger control of vascular risk factors in an attempt to help prevent dementia."

"It's been observed for years that people who had a stroke and later develop Alzheimer's typically don't do as well with their Alzheimer's, and have a faster rate of decline," says Bill Thies, PhD, vice president of medical and scientific affairs for the Alzheimer's Foundation. "This study is high-quality confirmation of data we've seen before that suggests the development of dementia is, in many cases, perhaps a combination of effects" -- partly from the brain changes that are associated with Alzheimer's and partly from those that result from problems with circulation and blood vessels.

The take-home message: "Take care of your blood vessels if you want to retain as much function as possible in your later years," Thies tells WebMD. That means following the same "heart-smart" regimen of eating a healthy diet, getting regular exercise, not smoking, and controlling blood pressure, cholesterol, weight, and blood sugar as you would to prevent heart disease, cancer, diabetes, and other health threats.

This strategy may be especially important if you consider that these silent strokes occur nearly 15 times more often than classic strokes -- yet many people are completely unaware they have had them. According to data presented two years ago to the American Stroke Association, silent strokes afflict about 4% of the U.S. population at some point in their lives.

Although rare before age 30, the chance of having silent strokes doubles every 10 years, say researchers. By the time people reach their 70s, one in three has experienced at least one silent stroke per year -- usually showing no obvious initial symptoms and detectable only through a brain scan. But the injury accumulates over time, leading to symptoms of dementia such as memory and thinking impairments, as well as difficulty in walking.

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