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National study reports decreased dementia prevalence

Dementia prevalence among Americans age 65 and older decreased significantly between 2000 and 2012, according to a study published in JAMA Internal Medicine on November 21, 2016. Results from the nationally representative Health and Retirement Study (HRS) found that dementia prevalence decreased from 11.6 percent in 2000 to 8.8 percent in 2012, representing a relative decrease of about 24 percent.

Dr. Kenneth M. Langa of the University of Michigan and colleagues analyzed responses from approximately 10,500 HRS participants aged 65 or older in 2000 and 2012. They found that more years of education were associated with the decline in prevalence, but could not completely explain it. The average number of years of education increased from 11.8 to 12.7 between the cohorts. The decrease is similar to reports from other recent surveys. In this study, the decrease in dementia prevalence was noted for both men and women, despite an increase between 2000 and 2012 in cardiovascular risk factors such as high blood pressure, diabetes, and obesity.

The authors note that it will be important to continue to monitor the incidence and prevalence of dementia as the number of older adults, who are most at risk, continues to grow in coming decades. The findings from this study suggest rates of dementia can move in a positive direction, but more research will be needed to pinpoint the full set of social, behavioral, and medical factors that directly influence the development of and reduced risk for Alzheimer’s and other dementias.

The HRS, launched in 1992, is a longitudinal study of people 50 and older funded by the NIA with contributions from the Social Security Administration. It currently follows more than 22,000 individuals, collecting data every two years, from pre-retirement to advanced age. The study consists of extensive interviews with participants, who are asked detailed questions about their health, economic status, social factors, cognitive ability, and life circumstances. The interviews also include a set of physical performance tests, body measurements, blood and saliva samples, and a psychosocial questionnaire.

Reference: A Comparison of the Prevalence of Dementia in the United States in 2000 and 2012 by Kenneth M. Langa, et al. JAMA Internal Medicine. November 21, 2016.