Oldest-old (85+ age group)

The oldest-old is a demographic and gerontological term for individuals aged 85 and above, the fastest-growing segment of most high-income country populations. This group shows heterogeneous functional and cognitive trajectories; a substantial minority maintains high functional capacity into the late eighties and beyond, a phenomenon sometimes termed successful aging. Compared with younger old adults (65–84), the oldest-old display distinct epidemiology: traditional cardiovascular risk factors such as hypertension and elevated LDL-C lose predictive power, while markers of physical function, nutritional status, and resilience become stronger mortality predictors. Studying this group is methodologically complicated by survival bias — those who reach 85 are a selected population — which may inflate associations between traits observed at that age and longevity.