Study IDs Dementia Risk Factors in Those Older Than 90 Years

MONDAY, Aug. 10, 2026 (HealthDay News) — Dementia risk factors persist even in nonagenarians, according to a study published online Aug. 4 in The Lancet Healthy Longevity.

Hilary L. Colbeth, Ph.D., from the University of California (UC) Davis, and colleagues examined dementia incidence and its risk factors in people older than 90 years as part of the LifeAfter90 study. The analysis included data from 805 participants (median age, 92 years).

The researchers found that during a mean follow-up of two years, 17 percent of participants developed dementia and 37 percent died. The age-standardized incidence rate of dementia was 116.82 cases per 1,000 person-years. Dementia risk was higher in female participants than in male participants (subdistribution hazard ratio [sHR], 1.89) and Black versus Asian participants (sHR, 1.75). Risk was lower in APOE ε2 carriers than in noncarriers (sHR, 0.39). There was a nonsignificant trend toward higher risk in APOE ε4 carriers versus noncarriers, particularly among men. There were no significant differences in risk by education.

“Doctors need to know that certain groups are at higher or lower risk,” senior author Rachel Whitmer, Ph.D., also from UC Davis, said in a statement. “We can”t just assume that someone from a high-risk group makes it to 90 without dementia and they”re in the clear. We need to talk about risk reduction for everyone.”

Abstract/Full Text