Prevalence of depression and its treatment in an elderly population - The Cache County study

Background: Previous estimates of the prevalence of geriatric depression ha ve varied. There are few large population-based studies; most of these focu sed on individuals younger than 80 years. No US studies have been published since the advent of the newer antidepressant agents. Methods: In 1995 through 1996, as part of a large population study, we exam ined the current and lifetime prevalence of depressive disorders in 4559 no ndemented individuals aged 65 to 100 years. This sample represented 90% of the elderly population of Cache County, Utah. Using a modified version of t he Diagnostic Interview Schedule, we ascertained past and present DSM-IV ma jor depression, dysthymia, and subclinical depressive disorders. Medication use was determined through a structured interview and a "medicine chest in ventory." Results: Point prevalence of major depression was estimated at 4.4% in wome n and 2.7% in men (P=.003). Other depressive syndromes were surprisingly un common (combined point prevalence, 1.6%). Among subjects with current major depression, 35.7% were taking an antidepressant (mostly selective serotoni n reuptake inhibitors) and 27.4% a sedative/hypnotic. The current prevalenc e of major depression did not change appreciably with age. Estimated lifeti me prevalence of major depression was 20.4% in women and 9.6% in men (P<.00 1), decreasing with age. Conclusions: These estimates for prevalence of major depression are higher than those reported previously in North American studies. Treatment with an tidepressants was more common than reported previously, but was still lacki ng in most individuals with major depression. The prevalence of subsyndroma l depressive symptoms was low, possibly because of unusual characteristics of the population.