Dementia risk remains significant after age 90, study shows
A study of adults over 90 found that dementia risk is still shaped by sex, race, and genetics, with women and Black participants facing higher risks. Some individuals remained cognitively healthy despite carrying major risk factors, offering clues to brain resilience. The findings come from the ongoing LifeAfter90 study.
The LifeAfter90 study, launched in 2018, tracks Kaiser Permanente members who enrolled without dementia at age 90 or older. Researchers conduct cognitive assessments every six months, and some participants' medical histories reach back to the 1960s, providing an unusually deep longitudinal view. The cohort of over 800 people, with a median age of 92, is notably diverse for research at this age.
The study's findings confirm that established risk patterns persist into extreme old age. Women showed roughly double the dementia risk of men, while Black participants faced a 75% higher risk than Asian participants. The protective APOE2 gene variant continued to shield carriers past 90, and a subset of participants maintained cognitive health despite carrying major risk factors, suggesting possible mechanisms of brain resilience worth investigating.
As global lifespans extend, with projections of 230 million people over 90 by 2100, this research could help shape healthcare planning for an aging population. Families and clinicians may use these findings to better anticipate dementia risk in very old relatives, while the identification of resilient individuals could eventually inform prevention strategies. However, the observed racial disparities may also highlight broader questions about lifelong healthcare access and social determinants that warrant further attention.