Early impact of depression symptoms on the decline in activities of daily living among older Japanese: Y-HALE cohort study

OBJECTIVE: It is well known that depression deteriorates basic activities of daily living (ADLs), such as eating and bathing, among the elderly, but little is known about the early impact of depression symptoms on the next higher level of functioning, namely higher-levels ADLs, such as instrumental self-maintenance, intellectual activities, and social roles. The objective of this study was to determine whether symptoms of depression are associated with a subsequent decline in higher-level ADLs within a 12-month period of time. METHODS: The study cohort consisted of a random sample of 587 non-institutionalized adults aged ≥ 65 years living in Yamanashi prefecture, Japan. The baseline survey was conducted in 2003. After 12 months, a mailed follow-up survey evaluated changes in higher-level ADLs (follow-up rate 98.6%). RESULTS: After adjusting for sociodemographic and behavioral confounders, logistic regression indicated that baseline severe depression symptoms were associated with a 3.2-fold (95% confidence interval 1.6-6.3) higher chance of a subsequent decline in higher-level ADLs compared to those without severe depression symptoms. The presence of severe depression symptoms was selected by stepwise logistic regression in all models, except for the model with intellectual activities as an outcome, while other lifestyle factors were not selected. CONCLUSIONS: Symptoms of severe depression may adversely affect higher-level ADLs even in a relatively short time-frame. In addition, the early effects of depression symptoms may be stronger than those of other traditional lifestyle risk factors. Monitoring a wide range of ADLs in elderly individuals showing signs of depression may be important to prevent a functional decline in health and the need for long-term care.