The Link Between Alzheimer’s and Stroke

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A growing body of evidence suggests that stroke and even stroke risk factors are related to cognitive decline. People who have had a stroke have nearly double the risk of developing Alzheimer’s disease. In fact, the chances of having a stroke in midlife are linked to the chances of developing dementia down the road. The Framingham Heart Study—which has followed thousands of adults over three generations in the Boston area—shows that obesity, high waist circumference, high waist-to-hip ratio, and high body mass index affect your risk of both stroke and dementia.

In a study published in the journal Stroke, researchers assessed stroke risk factors such as hypertension, diabetes, and smoking in more than 2,000 men and women to determine their 10-year risk of stroke. The study found that as stroke risk increased, cognitive performance declined, especially in “executive” functions, such as attention, organization, visual-spatial memory, and abstract thinking.

The landmark Nun Study, which began in 1986, showed the impact of even tiny strokes on cognitive function. Conducted with 678 Catholic sisters ages 75 to 107, the study has provided a rare opportunity to assess dementia risk factors in these women and then link them with physical changes in the brain verified after their deaths. Findings indicate that nuns whose autopsies showed significant brain evidence of Alzheimer’s disease were up to 20 times more likely to have shown symptoms of dementia when they were alive if they also had brain evidence of tiny strokes. This suggests that coexisting stroke-related (or vascular) damage in the brain heightens the impact of Alzheimer’s on cognitive function.

And a report from the Archives of Neurology further revealed that people with a history of a full-blown stroke were about 60 percent more likely to receive a diagnosis of Alzheimer’s disease than were people with no history of stroke. The study’s authors speculated that the same vascular diseases that cause stroke may also contribute to the development of Alzheimer’s disease, or that stroke may accelerate the onset of Alzheimer’s symptoms in people who are already predisposed to developing dementia.