Objectives: To examine the relationship between persistently high depressive symptoms and long-term changes in functional disability in elderly persons.
Design: A community-based, prospective, observational study.
Setting: Participant data from the Cardiovascular Health Study.
Participants: From the overall sample of 5,888 subjects, three types of participants were identified for this study: (1) persistently depressed individuals, who experienced an onset of depressive symptoms that persisted over 4 years (n=119); (2) temporarily depressed individuals, who experienced an onset of depressive symptoms that resolved over time (n=259); and (3) nondepressed individuals, with persistently low depressive symptoms throughout the follow-up period who were matched on baseline activity of daily living (ADL) scores, sex, and age to the previous two groups combined (n=378).
Measurements: Four consecutive years of data were assessed: validated measures of depression (10-item CES-D), functional disability (10-item ADL/instrumental ADL measure), physical performance, medical illness, and cognition.
Results: The persistently depressed group showed a greater linear increase in functional disability ratings than the temporarily depressed and nondepressed groups. This association between persistent depression and functional disability was robust even when controlling for baseline demographic and clinical/performance measures, including cognition. The persistently depressed group had an adjusted odds ratio (OR) of 5.27 (95% confidence interval (CI) 3.03-9.16) for increased functional disability compared with the nondepressed group over 3 years of follow-up, whereas the temporarily depressed group had an adjusted OR of 2.39 (95% CI=1.55-3.69) compared with the nondepressed group.
Conclusion: Persistently elevated depressive symptoms in elderly persons are associated with a steep trajectory of worsening functional disability, generating the hypothesis that treatments for late-life depression need to be assessed on their efficacy in maintaining long-term functional status as well as remission of depressive symptoms. These results also demonstrate the need for studies to differentiate between persistent and temporary depressive symptoms when examining their relationship to disability.