More than 40% of older adults in the United States today may develop dementia by the age of 95, with higher risk in women, Black adults, and carriers of the apolipoprotein ε4 (APOE ε4) gene variant, according to the results of a study issued yesterday by Nature Medicine.
Researchers projected a near-doubling of new annual dementia cases over the next four decades—from about 514,000 in 2020 to about 1 million in 2060—a trend largely driven by the sizable baby boom generation reaching older ages.
“Previous studies suggest that 11-14% of men and 19-23% of women in the United States will develop dementia during their lives,” wrote Michael Fang, Ph.D., M.H.S., at Johns Hopkins Bloomberg School of Public Health, and colleagues. “However, these estimates were based on older data with limited dementia ascertainment, potentially resulting in underestimation. Racial disparities in the lifetime risk of dementia are also poorly characterized, as population-based analyses have typically been limited to Non-Hispanic White populations.”
Fang and colleagues used data from 15,043 diverse participants of a long-running community study (median follow-up of 23 years) to estimate the lifetime risk of dementia from ages 55 to 95; all included participants were dementia-free at age 55. During the study follow-up, 3,252 participants developed dementia, 5,803 died without dementia, and 2,131 left the study.
The researchers applied the data from the study to U.S. census projections to evaluate the potential number of incident dementia cases from 2020 to 2060. They reported the following:
- The lifetime risk of dementia after age 55 years was 42%.
- The cumulative incidence of dementia remained low up to age 75 (4%), then increased progressively faster.
- The median age of dementia diagnosis was 81 years.
- Lifetime risks were higher in women versus men (48% vs. 35%) and Black adults versus White adults (44% vs. 41%).
- Adults with two copies of the APOE ε4 alle had a substantially higher lifetime risk of dementia (59%) compared with those with one copy (48%) and those with no copies (39%), with differences seen beginning at about 70 years of age.
“Our results suggest that the current lifetime risk of dementia may be substantially higher than previously thought, emphasizing the importance of prevention throughout the life course,” Fang and colleagues wrote. “Policies focused on optimizing cardiovascular health and preserving hearing may be particularly important. Accumulating data from clinical trials have linked healthy lifestyle behaviors, the absence of vascular risk factors, and hearing rehabilitation with improved cognitive outcomes.”
For related information, see the Psychiatric News article “New Medication, Staging Criteria Signal a Potential Shift in Alzheimer’s Care.”
(Image: Getty Images/iStock/Jacob Wackerhausen)
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