Understanding the Mechanisms of Change in a Lifestyle Intervention for Older Adults.

Purpose of the Study: This study investigated the mechanisms of change underlying an activity-based lifestyle intervention, an occupational therapy program aimed at promoting healthy habits, and routines in older adults. We examined two activity-relevant factors as potential mediators linking the intervention to reduced symptoms of depression: activity frequency and global perceptions of activity significance. Social connections and perceived control were assessed to understand how activity-related factors relate to reduced symptoms of depression. Design and Methods: The sample consisted of 460 multiethnic community-dwelling older adults aged 60-95 years. Participants were randomly assigned to a 6-month lifestyle redesign intervention (n = 232) or a no-treatment control (n = 228) condition. After the 6-month period, 360 individuals completed post-testing. Latent change score models were used to represent changes from baseline over the experimental interval. Structural equation models were applied to examine the indirect effects of the intervention on reduced depressive symptoms. Results: The results demonstrated significant indirect effects from intervention receipt to decreased depressive symptoms via increased activity frequency and activity significance. Higher activity frequency was linked to fewer depressive symptoms via heightened social connections, whereas increased activity significance was associated with fewer depressive symptoms via enhanced perceived control. Implications: The results support basic principles of occupational therapy by highlighting important mediating roles of activity frequency and activity significance in reducing depressive symptoms. Understanding of these change mechanisms can help optimize activity-centered interventions to reduce depressive symptoms.