Background Depression is one of the most common mental disorders in old age. In order to assess future needs of the healthcare system for prevention and treatment, information on epidemiology of depression among the highest age groups is required. However, most previous studies just focused on prevalence and incidence rates of late life depression across the entire old age.

Methods For a population-based sample of 1265 elderly individuals aged 75 years and older, prevalence and incidence rates as well as risk factors of depression were determined. Individuals were requested every 1.5 years over six waves. Depression was assessed dimensionally by the CES-D (Center of Epidemiologic Studies Depression Scale) and categorically by the SCID (Structured Clinical Interview for DSM-IV). The prevalence rates were 1.0% for Major Depression, 2.5% for Minor Depression according to DSM-IV and 38.2% for depressive symptoms according to CES-D. The rates increased for Minor and depressive symptoms with rising age. Risk factors were divorced or widowed marital status, low educational level, poor self-rated health status, stressful life events, and poor social network. The incidence rates were 6.9 per 1000 person-years (py) for Major Depression, 16.6 per 1000 py for Minor Depression and 33.9 per 1000 py for depressive symptoms.

Discussion Since depressive symptoms are common in oldest age and associated with broad categories of risk factors, latest-life depression represents an important public health issue. Employment of comprehensive geriatric assessment to ascertain depressive symptoms and its concomitants could help to improve treatment success.