Scientists have found that disparities in dementia risk persist even in extreme old age, reports infohub.kz.
Researchers from the University of California, Davis (UC Davis Health) and Kaiser Permanente published findings from the long-term LifeAfter90 study in The Lancet Healthy Longevity. Launched in 2018, the project focuses on cognitive health in the oldest old. The team analyzed medical records of over 800 participants who were free of dementia at enrollment, with an average age of 92. Some participants had outpatient records dating back to the 1960s.
The results show that differences in dementia risk seen at age 65 persist after 90. Women over 90 are about twice as likely to develop dementia as men of the same age. The study also found significant racial and ethnic disparities: Black participants had a 75% higher risk than Asian participants. Hispanic participants also showed elevated rates.
The APOE gene continues to play a key role in old age. The protective APOE2 variant reduces dementia risk by 60% even after 90. In contrast, APOE4 doubles the risk in men and Black participants. Senior author Rachel Whitmer and first author Hillary Kolbet emphasized that reaching 90 without cognitive impairment is not enough to rule out risk, so prevention should continue throughout life.