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Stroke May Boost Chance of Alzheimer's

News Stroke May Boost Chance of Alzheimer's Charleston Gazette - December 17, 2003 MILWAUKEE - One of the best ways to avoid getting Alzheimer’s disease may be to ward off another devastating neurological disorder: stroke. Research published today found that people who had suffered a stroke were about 60 percent more likely to develop Alzheimer’s disease than those who had never had a stroke. And the risk was much higher among those who major risk factors for stroke and heart disease. The research ties together the two most disabling disorders of the brain and suggests that measures taken to prevent one may also help prevent the other. For years, doctors have known that people with poor vascular health were at higher risk for developing a stroke. And people who have had strokes are at greater risk for developing vascular dementia, a disease that is similar to Alzheimer’s disease, but which is caused by a different mechanism. Both vascular dementia and Alzheimer’s disease involve the progressive loss of memory and impairment of cognitive function. Vascular dementia, which is the second most common dementia after Alzheimer’s, has several forms, but all involve poor neurovascular health that leads to a lack of blood supply to the brain. Alzheimer’s, on the other hand, develops after clumps of misformed proteins form around and inside brain cells. Over the years, doctors have changed their thinking about dementia. "There was a time 30 or 40 years ago when almost everyone with dementia was thought to have vascular dementia," said study co- author Lawrence Honig, an associate professor of clinical neurology at Columbia University Medical Center. Doctors since have come to realize that the leading cause of dementia is Alzheimer’s, which now affects 4.5 million Americans and is expected to increase dramatically in the next two decades as the population ages. It is found in 10 percent of all people over the age of 65 and half of those over 85. The study, which appears in the Archives of Neurology, offers two explanations of how stroke and Alzheimer’s are linked. One theory is that poor vascular health in the brain may accelerate the symptoms of Alzheimer’s. Honig used the analogy of a car engine that is not working well, but still is getting along. Suddenly, it gets a tank of bad gas, causing it to sputter and die. The connection between stroke and Alzheimer’s has been noted in a few other studies, in particular the ongoing Nun Study of about 700 members of the School Sisters of Notre Dame, said Piero Antuono, a professor of neurology at the Medical College of Wisconsin. The Nun Study found that small strokes layered on top of Alzheimer’s disease can bring about symptoms of dementia much sooner. "It suggests if your brain is weakened by a stroke, your brain reserve is less," Antuono said. "Having two brain diseases is much worse than having one." That idea suggests there are two distinct causes, both leading to a decline in cognitive function. However, the Columbia study also supports the possibility there may be a common underlying physiological cause that makes some people more prone to both stroke and Alzheimer’s. That’s a theory now being studied by Robert Dempsey, and other researchers at the University of Wisconsin-Madison. In October, he presented findings from a small study of stroke- prone patients. Looking at the genetic make up of the plaque in their carotid arteries, Dempsey found two proteins that are precursors to amyloid- beta, the protein that builds up in clumps in the brains of people with Alzheimer’s. The finding, which still needs to be confirmed with a larger group of patients, suggests that stroke and Alzheimer’s may have a common cause.

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