Background. Although major depression is a common condition across the age range, there is some evidence from clinical studies that it may be more persistent and disabling in older adults. This study examined the demographic, socio-economic and clinical factors associated with major depression and with persistence of depressive symptoms at 2- and 4-year follow-ups in a large population sample of middle-aged and older adults.

Method. In a sample of 9747 participants aged over 50 in the 1996 wave of the US Health and Retirement Study, the authors assessed the 12-month prevalence of major depression using the Composite International Diagnostic Interview – Short Form (CIDI-SF). Significant depressive symptoms at the time of 1996, 1998 and 2000 interviews were assessed using a short form of the Center for Epidemiological Studies Depression Scale (CES-D).

Results. The 12-month prevalence of CIDI-SF major depression was 6·6%. With age, prevalence declined, but the likelihood of significant depressive symptoms at follow-ups increased. Both prevalence and persistence of significant depressive symptoms at follow-ups were associated with socio-economic disadvantage and physical illness. Persistence of depressive symptoms at follow-ups was also associated with symptoms of anhedonia, feelings of worthlessness, and thoughts of death at baseline.

Conclusions. Sociodemographic, physical health and a specific profile of depressive symptoms are associated with a poorer course of major depression in the middle-aged and older adults. These indicators may identify a subgroup of patients in need of more careful follow-up and intensive treatment.