tions and measurement issues. No studies thus far have tracked trends in late-life participation in society. Instead, most studies measure difficulty or the use of help with daily activities (related either to personal care or to living independently). Recent studies have also highlighted disparities in trends across demographic and socioeconomic groups^6–8.

Since these theories of population aging have been proposed, understanding of disability has evolved from a classic medical model, which attributes disability to underlying chronic conditions and impairments, to one that recognizes the fundamentally social and environmental components of disability^9,10. As such, recent hypotheses as to the reasons for late-life disability trends have included the influence of chronic disease trends and related medical care; shifts in underlying physical, cognitive, and sensory functioning; changes to the environment, such as technological aids and rehabilitation technologies; and demographic shifts. This paper reviews the most recent evidence on trends in late-life disability in the United States, disparities therein, and current understanding of the reasons for those trends.

Studies of the 1960s and 1970s suggested that longer life implied worsening health, as measured by increases in self-reported disability and chronic disease^11,12. Some have questioned whether these increases were due to changing social forces during the period that made reports of disability more acceptable¹³.

The evidence for the 1980s and early 1990s was mixed, with Manton and colleagues reporting large declines in disability^14,15 and Crimmins and colleagues concluding that there was no clear ongoing trend¹⁶. At the request of the National Institute on Aging, the Committee on National Statistics of the National Research Council held a workshop to review the data and methods used to determine trends in disability at older ages¹⁷. The workshop report concluded that there had been modest declines in the proportion of older people with limitations in instrumental activities of daily living (IADLs) but inconsistencies across surveys in trends in activities of daily living (ADLs).

In the decade since that workshop more than a dozen studies have focused on late-life disability trends. A recent review⁴ highlighted methodological considerations in the comparison of trends in prevalence across surveys and reported findings for a range of outcomes, including physical, cognitive, and sensory limitations as well as ADL and IADL disabilities. The authors found that of the 16 studies identified, 8 unique surveys were analyzed: for the purposes of trend analysis, 2 were rated as good, 4 were rated as fair, 1 was rated as poor, and 1 was rated as mixed (fair or poor,