Stability and change in level of probable depression and depressive symptoms in a sample of middle and older-aged adults

Background: Findings from studies investigating depression in adults in late life are mixed due to a lack of large longitudinal studies with the power necessary to yield reliable estimates of stability or change. We examined the long-term stability of probable depression and depressive symptomology over a 13-year period in the Dynamic Analyses to Optimize Ageing (DYNOPTA) project. Methods: Community-living participants (N = 35,200) were aged 45-103 at baseline, predominantly female (79%), partnered (73%), and educated to secondary school only (61%) and followed for up to 13 years. Results: At baseline, increased age was associated with lower prevalence of probable depression and depressive symptomology. Over time, prevalence of probable depression was stable while levels of depressive symptomology reported a small decline. However, this finding was not consistent for all age groups; there was evidence for increasing levels of depressive symptomology, but not probable depression, as individuals aged. This effect was particularly notable among males aged 70 plus years. Conclusions: These results answer important questions relating to the longitudinal prevalence of probable depression and depressive symptomology in a sample of older Australians. These findings have policy implications for mental health service provision for older adults.