OBJECTIVE: Nonadherence to prescribed medications is a significant problem in the treatment of mood disorders. Previously proposed adherence models have not been sufficiently accurate in identifying patients who do not adhere to treatment. This study evaluated the importance of the social context in adherence by using a prospective, longitudinal analysis. Specifically, this study evaluated the effects of caregivers' causal beliefs about depression and their perceptions of stigma on three-month treatment adherence among patients with depression.

METHODS: Fifty patients with major depressive disorder and their primary caregivers were identified at a psychiatric hospital's outpatient clinic. Attributions for the causes of depression (either cognitive and attitudinal or medical and biological) and perceived stigma were assessed among caregivers at baseline, and patients' adherence was evaluated three-months after treatment began.

RESULTS: Data were available for 47 patients at follow-up. Caregivers' attribution of depression to cognitive and attitudinal problems significantly predicted patients' decreased adherence. However, the degree of patients' adherence was not predicted by caregivers' attributions to medical and biological causes and caregivers' perceived stigma.

CONCLUSIONS: The findings stress the importance of patients' social environment in determining treatment adherence and the necessity of educating caregivers about the impact that their causal attributions have on patients' behavior. Involving caregivers in treatment may improve their attitude toward patients with depression and, in doing so, enhance patients' adherence and outcome.