New study advances understanding of dementia after age 90

It may seem natural to assume that people experience cognitive decline after age 90, but until recently, researchers had limited evidence about how advanced age affects the brain. This major knowledge gap will need to be addressed as people live longer. By 2100, there could be around 230 million people 90 or older on Earth. As a result, scientists, clinicians and policymakers are seeking more information to help them support this expanding demographic.

Researchers at UC Davis Health and Kaiser Permanente have helped fill this knowledge gap by tracking a large group of 90+ year-olds since 2018 - the LifeAfter90 study. Their most recent findings, which were published in The Lancet Healthy Longevity delineate dementia risk disparities between genders and racial and ethnic groups. The study also revealed how older brains respond to genetic variables.

"We know from other studies, done in people 65 and older, that there are differences in dementia rates, and women tend to have higher risk, but nobody knew if that was true after 90," said Rachel Whitmer, UC Davis Health professor of public health sciences and neurology, chief of epidemiology and senior author on the study. "We need to understand who is most effected by dementia after 90 and how the main Alzheimer's risk gene (APOE) factors in."

LifeAfter90 participants are Kaiser Permanente members, 90 or older, who enrolled before they had any signs of dementia. Led by Whitmer, researchers have closely followed these patients, examining them every six months to track their cognitive health.