Low-income Americans age 55 to 84 are more likely to report functional limitations than those in higher income brackets. According to a study published in The New England Journal of Medicine, older Americans whose income falls below the poverty line are six times as likely to report limits on their physical activity.

The study was conducted by the National Institute on Aging (NIA), part of the National Institutes of Health, in collaboration with the University of California, Berkeley, and the University of Toronto.

Reports of functional limitations differed by income in age groups 55 to 64 years, 65 to 74 years and 75 to 84 years. A functional limitation is a condition that limits one or more basic physical activities of daily living (ADLs), such as walking, climbing stairs, reaching, lifting or carrying.

“We found that a ‘gradient of disability’ exists across the full socioeconomic spectrum, as functional limitations proved inversely related to household income,” says senior author Jack M. Guralnik, M.D., Ph.D., chief of the NIA’s Laboratory of Epidemiology, Demography and Biometry.

Improved understanding of the relationship between socioeconomic status and disability is critical as the U.S. population ages, Guralnik notes.

National Institute on Aging