Nearly half of adults over 65 improve in cognition or physical function over time

Average everyone together and aging looks like a straight line pointing down. Cognition fades. Walking slows. The body accumulates deficits. This is the story told by population averages, and it has shaped how we think about growing old.

But averages hide a lot. When Becca R. Levy, a professor of social and behavioral sciences at the Yale School of Public Health, stopped looking at group means and started tracking individual trajectories, a very different picture emerged. In a study published in the journal Geriatrics, Levy and co-author Martin Slade found that nearly half of adults aged 65 and older showed measurable improvement in cognitive function, physical function, or both over periods of up to 12 years.

The data behind the surprise

The study drew on the Health and Retirement Study, a federally supported longitudinal survey that tracks a nationally representative sample of older Americans. The researchers followed more than 11,000 participants, assessing cognition through a global performance test and physical function through walking speed -- a measure that geriatricians often call a "vital sign" because of its strong links to disability, hospitalization, and mortality.

Over the follow-up period, 45% of participants improved in at least one of the two domains. About 32% improved cognitively, 28% improved physically, and many exceeded thresholds considered clinically meaningful. When participants whose cognitive scores merely remained stable (rather than declining) were included, more than half defied the stereotype of inevitable deterioration.

"What's striking is that these gains disappear when you only look at averages," Levy said. "If you average everyone together, you see decline. But when you look at individual trajectories, you uncover a very different story."

The mindset effect

The researchers then asked what separated the improvers from the decliners. They hypothesized that age beliefs -- the positive or negative views about aging that people absorb from their culture -- might play a role. The data supported the hypothesis clearly.

Participants who held more positive age beliefs at the start of the study were significantly more likely to show improvements in both cognition and walking speed, even after the researchers controlled for age, sex, education, chronic disease, depression, and length of follow-up. The effect was not trivial: the association held across a large, diverse population and withstood adjustment for the most obvious confounders.

The finding builds on Levy's stereotype embodiment theory, which proposes that age stereotypes absorbed from culture -- through advertising, social media, casual conversation, birthday cards -- eventually become self-relevant beliefs that produce measurable biological consequences. In previous work, Levy has linked negative age beliefs to poorer memory, slower walking speed, higher cardiovascular risk, and biomarkers associated with Alzheimer's disease.

Not just the sick getting better

One potential objection to the findings is that the improvements might simply reflect sick people recovering -- a rebound effect rather than genuine gain. The researchers addressed this directly. Improvements were not limited to participants who started with impairments. Even among those with normal cognitive or physical function at baseline, a substantial proportion got better over time.

"Many people equate aging with an inevitable and continuous loss of physical and cognitive abilities," Levy said. "What we found is that improvement in later life is not rare, it's common, and it should be included in our understanding of the aging process."

What this does and does not prove

The study is observational, which means it can show that positive age beliefs are associated with improvement but cannot prove they cause it. People who are already improving for other reasons -- better social connections, more financial security, genetic advantages -- might also tend to view aging more positively. The arrow of causation could point in either direction, or both.

The measure of age beliefs was taken at baseline, before the follow-up period, which strengthens the temporal case for beliefs influencing outcomes. But it does not eliminate the possibility of unmeasured confounders. A randomized trial in which some participants received interventions to improve their age beliefs would provide stronger evidence -- and Levy has argued that such interventions, both individual and societal, are worth pursuing.

"Our findings suggest there is often a reserve capacity for improvement in later life," she said. "And because age beliefs are modifiable, this opens the door to interventions at both the individual and societal level."

The authors hope the findings will push back against the widespread assumption that aging is nothing but loss, and encourage policymakers to invest in preventive care, rehabilitation, and programs that support older adults' potential for resilience rather than managing their expected decline.