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THURSDAY, July 17, 2003 (HealthDayNews) -- Subtle changes deep within the brain can signal an increased risk of strokes, a new study suggests.
Scattered loss of the white matter through which nerve signals pass in the innermost sanctum of the brain is linked to a 50 percent increase in stroke risk over an extended period, says a report in the July 18 issue of Stroke.
The condition, called leukoaraiosis (LA), is so exotic that there is no entry for it in some older medical dictionaries, and "little is known about its development and progression, or its underlying mechanism or risk factors," says study author Dr. Jonathan Y. Streifler, director of the neurology unit at the Rabin Medical Center in Israel.
But that loss can be seen on computer tomography (CT) scans, and it is closely connected to the type of strokes caused by blockage of small arteries deep within the brain, the study reports.
The data came from a study designed to see whether surgery could reduce the risk of stroke for men with narrowing of the carotid arteries, the main blood vessels to the brain. All the 2,885 men in the study had CT scans as part of a thorough medical workup. Streifler and his colleagues looked at 685 men who had a second CT scan at least three years after the first scan.
When the study started, "the importance of LA was not appreciated," Streifler says. But two papers showing a link to increased stroke risk have since appeared, and this latest one "shows new LA development and points to its importance," he says.
Of the 685 men studied, only 89 had limited loss of white brain matter; 596 had no loss at all at the start of the project. After an average of 6.1 years, a second CT scan showed that 18 percent of the LA-free men had some white matter loss, with 3 percent having widespread loss.
During that time, 36 percent of the men with LA had at least one stroke, compared to 23.5 percent of those who had no white matter loss. And 11 percent of those with LA had more than one stroke, compared to about 6 percent of those who were LA-free.
After adjusting for other stroke risk factors, such as age and smoking history, the researchers concluded people who develop LA have a 50 percent higher risk of stroke than those who don't.
What does this mean for doctors and their patients?
"We cannot recommend a global policy, yet older people with stroke risk factors are obvious candidates for CT scans," Streifler says. "Yet this is at the discretion of their family physicians."
The problem with interpreting findings of LA is that "we really don't know very well what underlies these kinds of changes," says Dr. Larry Goldstein, director of the stroke center at Duke University and a spokesman for the American Heart Association.
LA "doesn't necessarily track with traditional risk factors for stroke," Goldstein says, but there are indications it might be associated with progression of Alzheimer's disease and other dementias.
"Physicians should be aware of its presence and importance when they order a CT scan for various reasons, especially when stroke risk factors are present in their patient," Streifler says. "It is likely (but not proven) that more careful management of these risk factors would decrease the risk of complications."