OBJECTIVE: Loneliness and social isolation are associated with depressive symptoms, cognitive and physical disabilities, and increased risk of mortality among older adults. Socially rewarding activities reduce loneliness, and neurobiological evidence suggests that these activities may activate neural reward systems in older adults to a greater extent than other rewarding experiences. The current study was designed to investigate whether engagement in social and interpersonal activities (i.e., exposure to social rewards) predicts subsequent increase in behavioral activation and reduction in depressive symptoms in reward exposure treatment for late-life depression.

METHODS: Forty-eight older adults without cognitive impairment and with major depression received nine sessions of "Engage" psychotherapy. Behavioral activation and depression severity were assessed by trained raters at baseline and weeks 6 and 9. Patients' weekly behavioral plans were categorized into three groups: 1) solitary activities; 2) social-group activities (attending a social gathering or a social setting such as church or a senior center); and 3) interpersonal-individual activities (engaging in an interpersonal interaction with a specific friend or family member).

RESULTS: Mixed-effects models showed reduction in depression severity and increase in behavioral activation over time. In linear regression models, a higher percentage of interpersonal-individual activities (but not solitary or social-group activities) predicted subsequent increase in behavioral activation and improvement of depression.

CONCLUSION: These findings highlight the importance of understanding the effects of engagement in specific types of rewarding activities in behavioral activation treatments for late-life depression. Exposure to socially rewarding interpersonal interactions could contribute to the efficacy of psychotherapy for late-life depression.