Dual Functionality in Later Life.

Gerontologists have long shown interest in both longevity and quality of life during later life, but considerable debate has ensued as scholars sought to integrate the two. Drawing from research on the topics of exceptional longevity, successful aging, and active life expectancy, we propose the concept of dual functionality to examine how humans reach advanced ages while maintaining physical and cognitive function. Dual functionality refers to being free of both physical and cognitive impairment. The loss of dual functionality challenges social networks to respond to the functional loss and is a harbinger of additional losses. Evidence of change in the percent of the older population maintaining dual functionality would be helpful for evaluating public health policies to aid quality of life during later life. This article is based on the first author's Robert W. Kleemeier Award Lecture at The Gerontological Society of America 2022 Annual Scientific Meeting.