A thorough analysis of three extensive population studies shows that over the last 40 years, age-adjusted dementia prevalence has dropped by 67% in the United States, confounding predictions estimating the number of cases to double by 2050.
“This analysis provides evidence to support our forecast from 2011, and subsequent Lancet Commission reports, which estimated that up to half of the anticipated increase in dementia due to the aging of the population could potentially be prevented through risk reduction interventions,” explains Deborah Barnes from the University of California San Francisco.
According to the National Long-Term Care Survey from 1984 to 2004, the prevalence of severe impairment decreased by 2.7% per year during this period — data from the U.S. The Health and Retirement Study shows that dementia prevalence declined by about 2.5% per year from 2000 to 2012. The National Health and Ageing Trends Study recorded a 3.7% drop per year between 2011 and 2021. These findings belie predictions of dementia doubling by 2050 since it came from applying the current dementia prevalence at each age range to the 2050 population, when there will be twice as many people over the age of 80 as there are now. In 1984, 30% of people between the ages of 85 and 89 had dementia; in 2024, it was 10%. Modifiable factors like exercise, smoking, hearing loss, and hypertension have a considerable effect on dementia risk, and shouldn’t be considered lightly. “The authors convey a message of hope,” said Jennifer Weuve from the Boston University School of Public Health.
