Dementia risk persists after 90, with women and Black adults facing higher rates

September 1, 2026 at 05:00 AM2 min

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A study of more than 800 people aged 90 and older found dementia risk continues to vary by sex, race, and genetics. Women had about twice the dementia risk of men, and Black participants faced a 75% higher risk than Asian participants. The findings come from the LifeAfter90 study, which has followed Kaiser Permanente members since 2018.

Key Facts

The LifeAfter90 study followed more than 800 people with a median age of 92, making it the first study of dementia after 90 in a highly diverse cohort.
Women aged 90 and older had about twice the dementia risk of men.
Black participants faced a 75% higher dementia risk than Asian participants.
The APOE2 gene variant is associated with a lower likelihood of developing Alzheimer's, while APOE4 increases risk.

Study Design

Participants in LifeAfter90 are Kaiser Permanente members who were at least 90 years old and showed no signs of dementia when they enrolled. Researchers evaluate participants every six months to monitor changes in cognitive health. Health records for some participants extend back to the 1960s, giving researchers an unusually extensive collection of medical information. The new analysis included records from more than 800 people with a median age of 92.

Disparities in Dementia Risk

Women age 90 and older had about twice the dementia risk of men. Researchers identified differences among racial and ethnic groups, with black participants facing a 75% higher risk than Asian participants. Hilary Colbeth, a UC Davis postdoctoral scholar and first author, said black and Hispanic participants had significantly higher dementia incidence rates than white and Asian participants. Rachel Whitmer, senior author and UC Davis professor, noted that disparities seen in people 65 and older continue after age 90.

Genetic Factors

Researchers examined the role of APOE, a gene strongly associated with Alzheimer's disease. APOE2 is considered protective and is associated with a lower likelihood of developing Alzheimer's, while APOE4 is known to increase risk. Whitmer said the study helps understand who is most affected by dementia after 90 and how the APOE gene factors in.