U.S. sees falling dementia rates since 2000: study

Americans are getting older and heavier, but a new study out on Monday said the percentage of U.S. seniors with dementia is dropping.

Kenneth Langa of the University of Michigan, Ann Arbor, and co-authors looked at data from the Health and Retirement Study, a large nationally representative group of U.S. adults to compare the prevalence of dementia in 2000 and 2012. The study included more than 21,000 adults 65 years or older.

In all, 11.6 percent of those interviewed in 2000 met the criteria for dementia, while in 2012, only 8.8 percent did. That corresponds to an absolute decrease of 2.8 percentage points and a relative decrease of about 24 percent.

"Our results, based on in-depth interviews with seniors and their caregivers, add to a growing body of evidence that this decline in dementia risk is a real phenomenon, and that the expected future growth in the burden of dementia may not be as extensive as once thought," said Langa.

The study, published online in the U.S. journal JAMA Internal Medicine, found that older adults in the 2012 group had, on average, about one year more education compared with those adults in the 2000 group.

It also concluded that improvements in treating cardiovascular risk factors may have played some role in the decrease.

"However, the full set of social, behavioral and medical factors contributing to the decline in dementia prevalence is still uncertain," the study wrote.

"Continued monitoring of trends in dementia incidence and prevalence will be important for better gauging the full future societal impact of dementia as the number of older adults increases in the decades ahead, as well as clarifying potential protective and risk factors for cognitive decline." Endit