Depressive disorder as a predictor of physical disability in old age.

OBJECTIVES: To determine whether the occurrence of depression predicts physical disability in older people.
DESIGN: A longitudinal epidemiological study with a follow-up of 5 years.
SETTING: A comparison between depressed and nondepressed participants. PARTICIPANTS: The series consisted of the persons who participated in the longitudinal epidemiological study on depression in old age performed in Ahtari, Finland. The first round of interviews and examinations was performed in 1984/1985 and the second round in 1989/1990. The study series (N = 786) was composed of persons functionally independent in activities of daily living (ADLs) during the first round and alive and participating in both rounds. MEASUREMENTS: Depression was determined according to DSM-III criteria. Physical functional abilities were measured with self-assessments of ability to manage ADLs.
RESULTS: In bivariate analyses, depression at the baseline did not predict lowering of functional abilities during follow-up, but the occurrence of depression with a long-term or relapsing course during follow-up and the onset of depression during follow-up in persons not depressed at the baseline predicted lowering of functional abilities during follow-up. The logistic regression analyses showed the presence of the following variables measured during the first round--older age, low basic education, poor self-perceived health, and occurrence of a physical disease--and the onset of the following diseases during follow-up--any physical disease, neurological disease, cerebrovascular disease, or depressive symptoms (in persons nondepressed at the baseline)--predicted lowered functional abilities after a follow-up of 5 years.
CONCLUSION: Depression that developed during the follow-up in previously nondepressed persons was associated with an increased risk for lowering of functional abilities, even when controlling for age, sociodemographic factors, physical diseases, and baseline disabilities. Depressed older people are at high risk for physical disability, and an individually planned program to maintain their functional abilities by training in ADLs and instrumental activities of daily living (IADLs) and physical exercise should be included in their treatment.