Purpose: The impact of major depression on quality of life (QOL) and aging experiences in older adults has been reported. Studies have demonstrated that the clinical diagnosis of major depression is the strongest predictor for QOL. We postulate that some findings are biased because of the use of inadequate instruments. Although subsyndromal depression is more prevalent than major depression, there are no reports on its impact on QOL or attitudes toward aging. In the present study we aim at assessing the association of major and subsyndromal depression on QOL and attitudes toward aging in a large international sample.
Design and methods: Our cross-sectional study assessed 4,316 respondents in 20 countries from five continents. The study used the World Health Organization Quality of Life (WHOQOL) Assessment for Older Adults, known as the WHOQOL-OLD; the brief version of the WHOQOL instrument, known as the WHOQOL-BREF; and the Attitudes to Ageing Questionnaire. Statistical analyses involved hierarchical multiple regression, as well as comparison of means.
Results: Even relatively minor levels of depression are associated with a significant decrease in all QOL domains and with a pattern of negative attitudes toward aging (overall WHOQOL-OLD R(2) change =.421). QOL and attitudes toward aging scores are lower as depression intensity is increased, even in subsyndromal levels (overall WHOQOL-OLD mean scores of 95.7 vs 86.4, p <.001). This phenomenon happens not only for clinically depressed individuals but also for subsyndromic individuals.
Implications: Present findings suggest that classifying a respondent as nondepressed is not sufficient and is still not informative about his or her QOL and attitudes toward aging status.