Depressive symptoms among older people: a 15-year follow-up

Depressive symptoms are common symptoms impairing the quality of life of older people. This population-based birth year cohort study investigated the prevalence of depressive symptoms and factors associated with them among home-dwelling older people.

A prospective, population-based 15-year follow-up study of the age cohort of 70-year-olds living in the city of Turku, Finland.

The data were collected in 1991 by a postal questionnaire that was sent to all residents of Turku, Finland, born in 1920 (n=1530). Follow-ups using the same procedure were conducted in 2001 and 2006. All examinations included an identical study protocol; the participants' self-reported health status/habits and depressive symptoms were investigated via a questionnaire. Afterwards, thorough clinical examinations including the Zung depression scale were conducted by a nurse and physician/geriatrician.

The mean of the Zung depression scale total score was 34 (SD 7.7) at the age of 70 and a significant increase was found in both re-examinations. At the age of 80 the mean of the Zung score was 35.8 (SD 7.5) while it was 37.6 (SD 8.9) at the age of 85 years. A similar increasing trend was found in the proportion of persons classified into the high Zung score group (≥45 points) indicating more depressive symptoms over the 15 year follow-up. Univariate and multivariate analyses showed that mostly functional and social factors were associated with subjectively reported depressive symptoms, while few associations were evidenced between depressive symptoms and medical conditions or poor health.

Our findings revealed an increase in prevalence of depressive symptoms throughout the course of the investigation. Our findings suggest that even in the absence of a diagnosis of major depression, depressive symptoms assume importance in the evaluation of the health status and need for health care services among older people.