Abstract
Positive psychology interventions have demonstrated efficacy in treating Major Depressive Disorder (MDD), but the relationship between dispositional optimism and antidepressant treatment response remains unclear. In this study, optimism (Revised Life Orientation Test, LOT-R) and depression severity (Hamilton Depression Rating Scale, HDRS) were assessed in healthy unmedicated MDD participants (N=86) and healthy controls (N=65). Treatment response (≥50% reduction in HDRS) was measured in 46 of these MDD participants after 8 weeks of open-label selective serotonin reuptake inhibitor (SSRI) treatment. MDD participants reported significantly lower pre-treatment optimism than healthy controls. Higher pre-treatment optimism, as well as greater increase in optimism (pre-treatment to 8 weeks), were associated with greater likelihood of being an SSRI responder versus non-responder (β=0.21, p=0.013; β =0.32, p=0.01, respectively), even when ratings of optimism/pessimism were excluded from depression severity/response ratings. The findings are consistent with the importance of aspects of positive psychology in treatment response. Possible mechanisms are discussed.