Warning Signs: A New Test to Predict Alzheimer's

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Researchers at the University of California, San Francisco (UCSF), and the University of Pittsburgh have developed the first screening tool that can help predict whether elderly patients are at low, moderate or high risk of developing dementia. The new test takes into account characteristic risk factors for dementia, including advanced age and the presence of genes associated with Alzheimer's, but also relies on lesser-known contributors such as patients' body weight and alcohol-drinking habits.

Detecting the earliest signs of memory loss and dementia — the broader category of age-related conditions of mental decline, up to 80% of which are Alzheimer's — has always been a major goal of researchers. While there is no cure for Alzheimer's, the earlier patients are diagnosed, the sooner they can make lifestyle changes that may help slow the progression of the neurodegenerative disorder. But so far, no test has proven dependable enough to help patients predict their true risk; even the presence of genes known to be associated with Alzheimer's does not reliably lead to the disease.

To date, the only other major screening tool for Alzheimer's was developed by Finnish scientists in 2006. However, that screen is targeted toward a younger population and designed to identify the highest-risk individuals in midlife. But considering how many factors may intervene between midlife and the 60s — the decade in which Alzheimer's typically sets in — Deborah Barnes, a professor of psychiatry at UCSF, says she wanted to develop a screen for the older population more likely to be at immediate risk of the disease.

"It's important to figure out who is at high risk and low risk, so that as we develop tools for prevention, we can try to target our prevention efforts at people with the highest risk for developing dementia," says Barnes, lead author of the new report published today in the journal Neurology. (Read "Advances for Alzheimer's, Outside the Lab.")

Barnes and her colleagues studied 3,375 patients age 65 years or older who were enrolled in a study analyzing heart disease and cognition. Researchers recorded which of the patients developed dementia in the six-year study period, then isolated the risk factors that appeared to make dementia more likely. Many factors were considered: age, genetic risk factors, mental health status, depression, physical fitness, alcohol consumption, fine motor skills and social support. In the end, only a handful of factors, arranged on a 15-point scale, emerged as being highly predictive of dementia.

Volunteers who scored eight points or higher on the index — which includes older age, worse cognitive function, some heart disease risk factors and the presence of genes linked to Alzheimer's — were at high risk of developing dementia within six years; 56% of these high scorers showed serious mental decline by the end of the study period. Of those scoring lower on the index, deemed at moderate or low risk, 23% were diagnosed with dementia. (Read "Alzheimer's Research Holds Promise.")

Many of the risk factors included in the new screen are familiar: advanced age and the presence of Alzheimer's genes (which are associated with the growth of fatty plaques and tangles in the brain that gum up neural connections), for example, have long been clearly linked to dementia. Even heart disease risk factors are somewhat expected, since recent studies show that the same conditions that boost the risk of heart attack, such as high cholesterol, hypertension and atherosclerosis, may also raise the risk of dementia; the theory is that whatever is causing fat deposits in heart vessels may also contribute to fat and protein deposits in the Alzheimer's brain.

Read "The Year in Medicine 2008: From A to Z."

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