Depressive symptoms and cognitive decline in elderly people. Longitudinal study.

Background: Depressive symptoms are associated with cognitive decline in elderly people, but the nature of their temporal relationship remains equivocal.

Aims: To test whether depressive symptoms predict cognitive decline in elderly people with normal cognition.

Method: The Center for Epidemiologic Study depression scale (CES-D) and the Mini-Mental State Examination (MMSE) were used to evaluate depressive symptomatology and cognitive functioning, respectively. A sample of 1003 persons aged 59-71 years and with a MMSE score of 26 or over was selected. Cognitive decline was defined as a drop of at least 3 points on the MMSE at 4-year follow-up.

Results: Baseline high levels of depressive symptoms predicted a higher risk of cognitive decline at 4-year follow-up. The MMSE score of participants with depression was more likely to fall below 26 at 2-year follow-up and to remain below at 4-year follow-up than the MMSE score of those without depressive symptoms. Persistent but not episodic depressive episodes were associated with cognitive decline.

Conclusions: High levels of depressive symptoms, when persistent, are associated with cognitive decline in a sample of elderly people.