Age and depression in late life: a longitudinal study of older Canadians

Zheng Wu, University of Victoria
Christoph M. Schimmele, University of Victoria

The literature indicates that, in comparison with non-senior adults, the prevalence of depression is lower for senior-aged persons. This conclusion is problematic for two reasons. First, the conclusions of most prior studies on late-life depression comes from interpretations of cross-sectional data. Second, there are several other methodological limitations surrounding the measurement and definition of late-life depression in much pre-existing research, including the exclusion of institutionalized seniors and a lack of controls for dementia patients. This current research resolves these limitations and thus presents improved estimates of age effects on late-life depression. There are two important conclusions. First, physiological decline mediates the age-depression relationship, making late-life depression a largely co-morbid condition. Second, the age-depression relationship for major depressive disorder (MDD) is non-linear, and persists after introducing controls for physiological decline. Our findings illustrate that MDD decreases between ages 65-79 and starts to increase around age 80-83.