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To contact David A. Snowdon, Ph.D., call Ann Kopanski at 606/257-3921.
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Stroke May Increase Risk of Alzheimer's Symptoms Stroke prevention may possibly ease the symptoms of Alzheimer's
Small strokes may produce and intensify the symptoms of Alzheimer's disease (AD), according to an article in this week's AD theme issue of The Journal of the American Medical Association (JAMA).
Because stroke is a common problem in the elderly and can affect mental function, David A. Snowdon, Ph.D., from the University of Kentucky's Sanders-Brown Center on Aging, Lexington, and colleagues investigated the role of stroke in producing and exacerbating the symptoms of Alzheimer's.
"Researchers have noted that significant numbers of individuals with abundant AD lesions in their brains do not have the symptoms of Alzheimer's. Furthermore, the symptoms of Alzheimer's vary dramatically in their severity, from mild impairment to severe disability. We hypothesized that stroke might explain these findings," Snowdon said in a separate interview.
The researchers found that even one or two small strokes in strategic regions of the brain can dramatically increase the risk of developing the symptoms of Alzheimer's, and also can increase the severity of those symptoms once they have developed.
Snowdon presented the findings today at an AMA media briefing on AD.
The researchers studied 102 college-educated Catholic sisters participating in the Nun Study who were 76 to 100 years old. Brain lesions of AD (neurofibrillary tangles and senile plaques) were measured at autopsy. A standard battery of neuropsychological tests was used to identify dementia (defined as impairment in memory, impairment in another area of thinking such as language, and impairment in social or daily function). People who suffer from Alzheimer's and other dementias may not remember recent events, may become easily lost in a familiar neighborhood, and may become confused over days and dates. Among the 61 women in the study who had abundant AD lesions, those with strokes were more likely to have dementia than those without strokes. In particular, women with small strokes in strategic regions of the brain were more than 20 times as likely to have dementia than women free from strokes. In the women who suffered a stroke, the researchers found small pockets of dead tissue
Among women who had abundant AD lesions, the prevalence of dementia was 93 percent in women with one or two small strokes in strategic regions of the brain, compared to only 57 percent in those without strokes. Women with small strokes had a higher prevalence of dementia even though they had fewer AD lesions than women without strokes. In addition, the symptoms of Alzheimer's were more severe in women with small strokes.
Because both small and large strokes were associated with atherosclerosis of the major blood vessel of the brain among all 102 participants, the risk of factors for stroke and atherosclerosis, such as hypertension, also might play some role. The researchers conclude that strokes "may play an important role in determining the presence and severity of the clinical symptoms of AD. Other manifestations of cerebrovascular disease, such as atherosclerosis, also may be involved in this process. Further research will be needed before it is known whether the prevention of cerebrovascular disease can mute the clinical expression of AD."
Editor's note: More information about the Nun Study may be obtained on-line by visiting its web page at: http://www.coa.uky.edu/nunnet # For more information: contact the AMA's Amy Fox at 312/464-4843. email: [email protected] AMA's web site: http://www.ama-assn.org
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