Depression Measured by the Zung Depression Status Inventory is Very Rare in a Finnish Population Aged 85 Years and over

The purpose of this study was to obtain information about the prevalence of depressive symptoms in a representative sample of elderly subjects aged 85 years and over. The study was carried out as a population-based interview study in the City of Vantaa in Finland. The Zung Depression Status Inventory (DSI) was used to evaluate various depressive symptoms in this study population. The DSI scores range from 20 to 80; the higher the score, the more severe the disturbance. In subjects interviewed (n = 467, 362 women, 105 men), the prevalence estimates of depression with cutoff scores used in earlier studies (40 and 48) were very low: 5.2% and 1.1%. Also, the mean DSI score (SD) was very low, 27.9 (6.4). The scores tended to decrease with age, although the differences were not statistically significant. The DSI means were 28.0 (6.1) for women and 27.3 (7.2) for men (p = .0349). Women had a greater risk of being classified as depressed on the DSI (odds ratio: 1.60, 95% confidence interval: 1.00-2.57, p = .049). Feelings of emptiness, personal devaluation, and depressive mood were the most common depressive symptoms. In conclusion, the present population-based study shows that subjective experience of depression is very rare in Finnish people aged 85+. Our results suggest that optimistic mood might give some protection against death.