Reaching 90 without dementia doesn’t mean you’re in the clear

People who reach their 90s without dementia might appear to have escaped much of the danger of cognitive decline. Until recently, however, scientists had relatively little evidence showing what happens to dementia risk at such advanced ages.

That gap is becoming increasingly important as lifespans rise around the world. By 2100, roughly 230 million people 90 or older could be alive worldwide, increasing the need for better information about how the brain ages in this rapidly growing population.

Researchers at UC Davis Health and Kaiser Permanente are helping address that question through the LifeAfter90 study , which has followed a large group of adults in their 90s since 2018. The latest findings, published in The Lancet Healthy Longevity , show notable differences in dementia risk by sex, race, ethnicity, and genetics.