Changes in deep brain tissue signal an increased risk for strokes
July 18, 2003
DALLAS - Changes in the brain's white matter, a common occurrence
among the elderly, increase a person's risk of having multiple strokes,
according to a report in today's rapid access issue of Stroke: Journal of
the American Heart Association.
White matter is the inner part of the brain, through which most of the
brain's nerve connections pass. Leukoaraiosis - the scattered loss of white
matter in the brain - is particularly associated with strokes caused by
blockages in small arteries deep in the brain (lacunar strokes).
"These small strokes can be devastating when they hit strategic
connections," says lead author Jonathan Y. Streifler, M.D., director of the
Neurology Unit at the Rabin Medical Center Golda Campus in Petach-Tikva,
Israel.
This is the first long-term follow-up study investigating the development
of leukoaraiosis and patient prognosis, Streifler says. The research, a
substudy of a large international study, found that people who develop the
condition were 1.5 times more likely to have a stroke than people without
the condition and almost twice as likely to have more than one stroke.
"Patients who developed leukoaraiosis were more likely to have multiple
strokes, which generally lead to increased disability, both physically and
mentally," Streifler says.
He and colleagues studied 685 patients with carotid artery disease who
participated in the 2,885-patient North American Symptomatic Carotid
Endarterectomy Trial (NASCET). The participants ranged in age from 34 to 84.
Only those with a follow-up computed tomography (CT) scan taken three years
or more from entry were included in the substudy. Although the multicenter,
randomized study began in the United States and Canada, it was later
expanded to other countries, including Israel, Australia and several in
Europe.
Previous findings from NASCET showed no link between leukoaraiosis and
the severity of narrowing of the arteries supplying the brain, Streifler
says. However, a recent study by the authors identified the presence of
leukoaraiosis (observed at a baseline CT scan) as a risk factor for stroke
and death from vascular disease, including heart attack.
"Leukoaraiosis is frequently found by computed tomography (CT) scans in
elderly patients, particularly those with dementia or a history of stroke or
hypertension," Streifler says. "Yet little is known about its development
and progression, or its underlying mechanisms and risk factors."
Of the 685 patients at entry in the study, 596 had no leukoaraiosis and
89 had limited white matter loss when they entered NASCET. During an average
follow-up of 6.1 years, 18 percent of the 596 patients initially free of
leukoaraiosis developed some loss of white matter and 3 percent had
widespread loss. The average age of patients who developed leukoaraiosis was
66.8. The average age of those who didn't was 62.9.
Significantly more of the patients who developed leukoaraiosis than those
who didn't had at least one stroke - 36 percent versus 23.5 percent. After
adjusting for gender, age, smoking history and diseases, including
hypertension and diabetes mellitus, the researchers found that the patients
who developed leukoaraiosis were 1.5 times more likely to have a stroke.
About 11 percent of patients who developed a loss of white matter had
more than one stroke, compared to about 6 percent of those without a loss.
Streifler says age appears to be the most important risk factor for
developing leukoaraiosis. Other factors that were somewhat associated with
increased risk were diabetes mellitus, leg pain and calf cramps caused by
poor blood circulation, and low levels of cholesterol. Hypertension, angina
attacks, and a previous heart attack also increased the risk, but not
significantly.
"There is not much we can do about age; however, controlling other risk
factors, such as hypertension and diabetes, may prevent or control
leukoaraiosis, and improve the outcome of patients," he says.
American Heart Association
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