Incidence and recurrence of late-life depression

Depression is common in old age. Nevertheless, few incidence studies have established how often depression occurs in elderly persons with and without a history of depression.

To determine the incidence and recurrence rates of depression in an elderly population.

A cohort study of community-dwelling elderly persons aged 56 years or older residing in Rotterdam, the Netherlands, performed between September 1993 and October 2005 and encompassing baseline and 2 follow-up examinations as well as continuous procedures. The study population consisted of 5653 participants free of dementia. Depression was identified through standardized psychiatric examinations, monitoring of medical records, registration of antidepressant use, and self-reported histories of depression. We categorized the depression as depressive syndromes, including DSM-IV-defined major depression, or clinically relevant depressive symptoms.

Incidence and recurrence rates for depressive syndromes as well as for depressive syndromes and symptoms combined. In addition to overall rates, sex- and age-specific rates were calculated.

During the follow-up period of 8 years on average, 566 depressive syndromes and 1073 episodes of clinically relevant depressive symptoms occurred. For depressive syndromes, the incidence rate was 7.0 (95% confidence interval, 6.0-8.3) per 1000 person-years and the recurrence rate was 27.5 (95% confidence interval, 23.7-32.1) per 1000 person-years. The incidence and recurrence rates more than doubled when episodes of depressive symptoms were included. The recurrence rate of depressive syndromes was equal for women and men, but all other rates were almost twice as high for women compared with men. No rates seemed to change with age.

The incidence rate of depression in the elderly population is low except when episodes of clinically relevant depressive symptoms are accounted for. Most late-life depression occurs in persons with a history of depression. Moreover, the recurrence rate of depressive syndromes does not differ between men and women.