Depressive symptoms in middle age and the development of later-life functional limitations: the long-term effect of depressive symptoms.

OBJECTIVES: To determine whether middle-aged persons with depressive symptoms are at higher risk for developing activity of daily living (ADL) and mobility limitations as they advance into older age than those without.

DESIGN: Prospective cohort study.

SETTING: The Health and Retirement Study (HRS), a nationally representative sample of people aged 50 to 61.

PARTICIPANTS: Seven thousand two hundred seven community living participants in the 1992 wave of the HRS.

MEASUREMENTS: Depressive symptoms were measured using the 11-item Center for Epidemiologic Studies Depression Scale (CES-D 11), with scores of 9 or more (out of 33) classified as significant depressive symptoms. Difficulty with five ADLs and basic mobility tasks (walking several blocks or up one flight of stairs) was measured every 2 years through 2006. The primary outcome was persistent difficulty with ADLs or mobility, defined as difficulty in two consecutive waves.

RESULTS: Eight hundred eighty-seven (12%) subjects scored 9 or higher on the CES-D 11 and were classified as having significant depressive symptoms. Over 12 years of follow-up, subjects with depressive symptoms were more likely to reach the primary outcome measure of persistent difficulty with mobility or difficulty with ADL function (45% vs 23%, Cox hazard ratio (HR)=2.33, 95% confidence interval (CI)=2.06-2.63). After adjusting for age, sex, measures of socioeconomic status, comorbid conditions, high body mass index, smoking, exercise, difficulty jogging 1 mile, and difficulty climbing several flights of stairs, the risk was attenuated but still statistically significant (Cox HR=1.44, 95% CI=1.25-1.66).

CONCLUSION: Depressive symptoms independently predict the development of persistent limitations in ADLs and mobility as middle-aged persons advance into later life. Middle-aged persons with depressive symptoms may be at greater risk for losing their functional independence as they age.