Study Links Physical and Mental Capacity to Disability Before Death

For many older adults, aging well means remaining independent—being able to do everyday activities like buying groceries or cooking dinner without help. A new Yale School of Medicine study, published in The Lancet Healthy Longevity, suggests that changes in mental, physical, or sensory capacity may be linked to a person’s future ability to perform these routine tasks.

Using data from 746 participants aged 70 and older in the Precipitating Events Project, a longitudinal study of community-dwelling older adults in South Central Connecticut, researchers examined changes in intrinsic capacity and disability during the 20 years before participants’ deaths. Intrinsic capacity comprises five areas of functioning: cognitive, sensory, locomotive, vitality, and psychological. Disability was measured by a person’s ability to shop, do housework, prepare a meal, take medications, and manage finances without assistance.

“By measuring intrinsic capacity, we’re not just looking at physical health,” explains Olivia Malkowski, PhD, postdoctoral associate in the Yale Department of Internal Medicine and first author of the study. “We’re looking at other things that are important to older adults, such as mental, cognitive, and sensory health, which are sometimes overlooked when we attempt to measure healthy aging.”

The researchers found that intrinsic capacity became more closely tied to disability as participants neared the end of life. Higher intrinsic capacity was linked to lower odds of disability beginning around 14 years before death, with the connection growing stronger as death approached.

The researchers used time-varying effect modeling, a statistical method, to examine how the relationship between intrinsic capacity and disability changed each month before death. Traditional statistical approaches often assume that the relationship between two variables stays the same over time, Malkowski explains.

“The method allowed us to see if and how the relationship between intrinsic capacity and disability strengthens, weakens, fades away, and peaks, month by month,” she says.

For Thomas Gill, MD, Humana Foundation Professor of Medicine (Geriatrics) and senior author of the study, the findings offer a simple way to think about why maintaining capacity matters. “Clinically, one can think of intrinsic capacity as a gas tank that drains as we age,” Gill says. “By intervening to bolster reserves, we can preserve that fuel and avert disability.”

Malkowski emphasizes that the findings are early evidence, not an immediate clinical blueprint. Still, the study points toward the value of tracking measures such as movement, cognitive function, depressive symptoms, and sensory health during regular checkups.

“This is early evidence that monitoring things like walking speed and memory as part of routine care could be useful for developing early interventions to help older adults preserve their independence and quality of life,” Malkowski says.