Exploring the effect of depression on physical disability: longitudinal evidence from the established populations for epidemiologic studies of the elderly.

TLDR

The study aimed to determine how depression affects the incidence of physical disability in older adults and to identify confounding and explanatory variables, including potential biological mechanisms. A six‑year prospective cohort of 6,247 adults aged 65 and older, all free of disability at baseline, was followed, with depression assessed by the CES‑D and annual measurements of mobility and activities of daily living disability. Depressed participants experienced a 39–45% higher risk of new disability after adjustment, and reduced physical activity and social contacts partially explained this excess risk.

Abstract

OBJECTIVES: This study examined the effect of depression on the incidence of physical disability and the role of confounding and explanatory variables in this relationship. METHODS: A cohort of 6247 subjects 65 years and older who were initially free of disability was followed up for 6 years. Baseline depression was assessed by the Center for Epidemiological Studies Depression Scale. Disability in mobility and disability in activities of daily living were measured annually. RESULTS: Compared with the 5751 nondepressed subjects, the 496 depressed subjects had a relative risk (95% confidence interval) of 1.67 (1.44, 1.95) and 1.73 (1.54, 1.94) for incident disability in activities of daily living and mobility, respectively. Adjustment for sociodemographic characteristics and baseline chronic conditions reduced the risks to 1.39 (1.18, 1.63) and 1.45 (1.29, 1.93), respectively. Less physical activity and fewer social contacts among depressed persons further explained part of their increased disability risk. CONCLUSIONS: Depression in older persons may increase the risk for incident disability. This excess risk is partly explained by depressed persons' decreased physical activity and social interaction. The role of other factors (e.g., biological mechanisms) should be examined.