Research suggests sharp drop in dementia rates

Experts: It's unclear if decrease will apply to Alzheimer's

Two new studies in The Lancet report decreasing dementia rates over the past 20 years, findings that suggest future generations may not struggle with the same dementia issues that currently plague the nation's elderly.

U.K. study: Dementia is decreasing among the 65+ group

For the first study, Cambridge Institute of Public Health researchers examined a study of 7,635 English and Welsh residents over age 64 conducted between 1989 and 1994. They compared it to their own study of 2,500 residents conducted between 2008 and 2011, which selected subjects from the same geographic areas and used similar data culling methods as the 1984-1994 study.

Based on the earlier study, researchers would have expected 8.3% of U.K. residents over age 64 to have dementia in 2011. However, the 2008-2011 study found that just 6.5% of U.K. residents over age 64 actually had dementia.

Danish study: Better health, education are improving dementia rates

For the second study, researchers at the University of Southern Denmark compared 1998 data on 2,262 93-year-old Denmark residents' mental health to 2010 data on 1,584 95-year-old residents' mental health. Researchers tested the participants' physical health as well as giving them dementia screening tests and cognitive exams.

Researchers found that only 17% of the 95-year-olds were consider severely impaired in 2010, compared with 22% of the 93-year-olds in 1998. In addition, their physical health was comparatively better in 2010.

Lead author of the Danish study told the Times that his study and the U.K. study "cautiously provides a basis for optimism" that "there is no one single magic bullet, but a series of things going in the right direction."

Medical community weighs in on studies' findings

Dallas Anderson—an expert on dementia at the National Institute on Aging (NIA)—said the studies are "rigorous" and provide "strong evidence" that the same trends are occurring in the United States.

However, another NIA expert—Richard Suzman—warns that the studies do not necessarily mean that the rate of Alzheimer's disease is also dropping. "Other forms of dementia could be going down, and Alzheimer's could be going up, for all I know," Suzman said.

In addition, Maria Carrillo—a vice president at the Alzheimer's Association—said she remains unconvinced that the trends were real or that they are applicable for U.S. residents. She recommended more research to be conducted in the United States (Kolata, Times, 7/16; Christensen et al., The Lancet, 7/11; Matthews et. al, The Lancet, 7/16).

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