Social support and locus of control as predictors of adherence to antidepressant medication in an elderly population

Objective: The authors examined whether social support and locus of control (LOC), either individually or jointly, would be associated with subsequent self-reported medication adherence and treatment barriers in a sample of depressed elderly patients. Methods: A group of 85 elderly patients with major depression was enrolled in the Mental Health Clinical Research Center for the Study of Depression in Later Life at Duke University and treated with a standardized algorithm. During the course of the study, participants completed measures of social support and internal locus of control (LOC). A little more than 1 year later, they completed general measures of medication adherence and treatment barriers. Results: Increasing subjective and instrumental social support and non-family interaction were associated with greater adherence among patients high in internal LOC but not among patients low in internal LOC. Less instrumental social support was associated with more treatment barriers among patients low in internal LOC but not among patients high in internal LOC. Conclusion: The relationship between social support and antidepressant medication adherence is moderated by beliefs about control over one's illness.