People older than 95 are nearly 20 times as likely to die with dementia as those who die between the ages of 65 and 69, according to a population-based study in England and Wales.
The study demonstrates that the prevalence of dementia increases with age and that those who reach the age of 80 without mental impairment can still become demented as they continue to age, suggesting that with increasing life expectancy the number of people with dementia also will increase, the investigators reported. Based on the results of the study, the researchers estimated that the number of people who die each year with dementia is 114,000 in England and Wales and 487,000 in the United States; these numbers will increase in 20 years to 138,000 andd 528,000, respectively.
The investigators analyzed patients in the Medical Research Council Cognitive Function and Aging Study, which enrolled 13,004 patients at centers in Liverpool, Newcastle, Nottingham, Oxford, and Cambridgeshire in England and Gwynedd in north Wales (PLoS Med 2006 Oct. 31 [Epub doi10.1371/journal.pmed.0030397]).
The study followed 2,558 patients who were classified as having severe cognitive impairment and 2,577 who were classified as having moderate/severe cognitive impairment as measured by the Geriatric Mental State interview.
Of the 768 people who had died within 1 year of their last interview, 30% were suffering from dementia. Of those ages 65–69 years, just 6% had dementia, but of those age 95 years and older, 58% were suffering from dementia, according to the study.
Led by Dr. Carol Brayne, professor of public health medicine at University of Cambridge, the researchers wrote that the prevalence of dementia demonstrated in their study suggests that prevention may have a negligible effect in an aging society.
“It may be that, although there will be a preventable component to dementia giving us a small and important absolute reduction in expectation of dementia at given ages, there is also a component that is not amenable to such types of prevention,” the authors said. “Researchers may be doing those who are aging now and themselves a disservice in the future if they assume, and project to the public, that dementia and cognitive impairment can be prevented altogether during increasingly long lives.
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