Functional Disability and Social Conflict Increase Risk of Depression in Older Adulthood Among Bolivian Forager-Farmers

Objectives: To present an explanatory framework for depression in older adulthood in a small-scale society. We propose that depression is a consequence of functional disability, which can reduce subsistence productivity, and resource transfers within and across generations. Social conflict can disrupt risk management strategies and should also be associated with depression. Methods: To evaluate depression among Tsimane forager-farmers of Bolivia, we developed a reliable interview based on focus groups and a review of validated depression scales. Older adults (mean ± SD age = 62 ± 9, n = 325) were recruited regardless of their health status. Demographic, economic, and medical data were collected during annual censuses and routine medical exams. Results: Depression is associated with reduced energetic status, greater physical limitations, and reduced subsistence involvement after controlling for potential confounds such as age, sex, number of reported unresolved conflicts, and market involvement. Depression is also associated with greater reported conflict, particularly with non-kin. Discussion: Tsimane depression is associated with functional disability, reduced subsistence productivity and interpersonal conflict, all of which can disrupt resource flows. Depression appears to be a response to conditions regularly experienced over human history, and not simply a byproduct of modernity