Mediating relationships within the Disablement Process model: a cross-sectional study of the oldest-old.

The Disablement Process model proposes a pathway for how chronic diseases in late life can lead to disability, with the variables in the main pathway designated as pathology, impairment, functional limitations, and disability. The model also suggests that psychosocial and contextual variables in the periphery of the model affect disability outcomes. The current study included 149 Swedish adults aged 86, 90, or 94 living in the community or in institutions who answered questions and performed tasks of physical and cognitive ability. A series of regressions were used to test the mediating role of variables within the main pathway of the model, as well as the ability of psychosocial variables to mediate main pathway relationships. Results indicated that physical limitations accounted for between 31 and 52% of the direct effects between impairments and disability, but delayed recall did not mediate these relationships. For the tests of psychosocial variables, mastery was a consistent mediator between impairments and functional limitations, and also mediated several relationships between functional limitations and disability variables. Depression and loneliness also mediated some of the relationships within the main pathway, but explained a smaller percentage of the total effects than mastery. The study concludes that the Disablement Process model is an effective biopsychosocial approach in describing and predicting disability in the oldest-old. In addition, the course of disability seems to be buffered by certain psychosocial variables, particularly feelings of mastery.