Reaching 90 healthy doesn’t end dementia risk
Making it to your nineties with a sharp mind sounds like a victory. But new research shows that dementia risk doesn’t disappear at that point, and for some groups it remains substantial.
The assumption has long been that those who stay cognitively intact into very old age have somehow escaped the worst. That picture is incomplete. The researchers studied people over 90 and found that dementia risk continues to be strongly shaped by sex, race and genetics, even in this age group.
Women and Black participants faced notably higher risks than men and white participants, even among those already in their nineties without dementia. At the same time, some individuals stayed cognitively healthy despite carrying major risk factors, such as the APOE4 gene variant associated with elevated Alzheimer’s risk. These individuals are scientifically intriguing: what is protecting them?
Resilience as a research question
The researchers suggest that people who remain cognitively intact despite risk factors may offer clues about brain resilience, the ability of the brain to resist or compensate for damage. That mechanism is still largely not understood.
What this means for longevity
The inequality in risk is striking from a longevity perspective. Biological aging does not proceed equally for everyone. Sex and genetic background appear to determine vulnerability even at very old age, making personalised risk assessment more relevant than ever.
The study is observational: it identifies factors associated with dementia risk but does not establish direct causation. Further research is needed to understand which protective mechanisms are active in people who age with their cognition intact.
Search terms to explore further: cognitive resilience oldest old, APOE4 dementia risk nonagenarians, sex differences dementia aging