Background: Depression is a common disorder in late life. As the elderly population continues to grow worldwide, depression is also likely to become an increasing health problem. The aim of this study was to examine changes in prevalence of depression in various age cohorts over an 11-year period.
Methods: This study involved two cross-sectional studies (HUNT 2 and HUNT 3) of all adult inhabitants of the Norwegian county of Nord-Trøndelag with an 11 year-interval between the two studies. The participants aged 45 years or above at HUNT 2 and with a valid depression rating at both HUNT 2 (baseline) and HUNT 3 (follow-up) (N = 16517), were included and divided into five-year age cohorts. Depression was measured by the depression subscale of the Hospital Anxiety and Depression Scale (HADS-D).
Results: A significant increase in depression was found in all age cohorts from 76 years at follow-up, with the greatest increase (9.6%) in the oldest age cohort (86-90 years at follow-up). The incidence of depression is increasing with age, with over 10% new cases in all age cohorts aged 81 years and above at follow-up. About 5% of the participants in all age cohorts reported depression at both measure points, and there is a decrease in recovery from depression from baseline to follow-up with increasing age.
Conclusions: We found increased prevalence of depression and a large number of new cases of depression in the oldest age cohorts.