New Studies Show Reduction in Dementia Rates Among Elderly

Rates of dementia among older populations in Britain and Denmark appear to have declined, according to two studies published in The Lancet. The British study surveyed two cohorts of people over age 65 in the same geographic areas in the period 1984-1994 and again in 2008-2011. About 8.3 percent of the first group was expected to have dementia in 2011, but the actual rate was 6.2 percent, wrote Carol Brayne, M.D., of Cambridge University, and colleagues, online July 17.

The Danish study tested cognitive and physical functioning among 2,262 people born in 1905 and among 1,584 born in 1915. "Despite being two years older at assessment, the 1915 cohort scored significantly better than the 1905 cohort on both the cognitive tests and the activities of daily living score, which suggests that more people are living to older ages with better overall functioning,” concluded Kaare Christensen, M.D., of the University of Southern Denmark, and colleagues.

Both studies suggest that cohorts born later have lower rates of dementia. Many factors might cause that difference, ranging from better health care or education among the younger groups to improved diets, less smoking, and reduced cardiovascular risk factors, although the studies did not speculate on reasons for the changes. Some commentators say the two studies are a hopeful sign the dire predictions of a coming onslaught of dementia may not be so dire. Others are not so sure. Replication of the studies in the U.S. and Canada may help answer that question.

For more in Psychiatric News about dementia, click here and here. Also see American Psychiatric Publishing's Clinical Manual of Alzheimer Disease and Other Dementias.

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