Reaching 90 without dementia doesn’t mean you’re in the clear
A study of people over 90 found that dementia risk remains strongly shaped by sex, race and genetics, with women and black participants facing notably higher risks. Intriguingly, some people stayed cognitively healthy despite carrying major risk factors, potentially offering clues to how the brain can resist dementia deep into old age.
People who reach their 90s without developing dementia may not be entirely safe from the risk of cognitive decline, according to new research. A study led by UC Davis Health and Kaiser Permanente has found notable differences in dementia risk based on sex, race, ethnicity, and genetics among individuals aged 90 and older. The LifeAfter90 study, which has tracked a large group of adults in their 90s since 2018, has revealed that women tend to have a higher risk of dementia compared to men, with women aged 90 and older having about twice the risk.
Additionally, black participants faced a 75% higher dementia risk than Asian participants. The gene APOE, which is strongly associated with Alzheimer's disease, also played a role in dementia risk. The protective APOE2 variant lowered dementia risk by 60%, while the risk-increasing APOE4 variant had more complicated effects, being associated with higher risk among men and approximately doubling dementia risk among black participants.
Despite having well-established dementia risk factors like hypertension and high cholesterol in their 60s and 70s, some individuals continued to remain cognitively healthy into their 90s. Understanding these biological and environmental mechanisms that protect certain individuals could potentially lead to new ways of reducing dementia risk for others.
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