Patient outcome expectancy during treatment was associated with improved clinical responses for both pharmacotherapy and cognitive behavioral therapy (CBT) in patients with major depressive disorder, according to results from a study published in the Journal of Affective Disorders.

The researchers recruited 104 outpatients with major depressive disorder who were randomly assigned to receive antidepressant therapy or CBT for a total of 16 weeks. Patient outcome expectancy was assessed over the course of the study using the Depression Change Expectancy Scale. Clinical responses included depression severity, which was measured using the Beck Depression Inventory-II and Hamilton Depression Rating Scale. Clinical evaluations were completed at baseline and at weeks 4, 8, and 16.

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After analysis, the researchers found that latent growth curve modelling showed improvement in expectancy across both pharmacotherapy and CBT treatment responses (mean slope, 1.47; P <.001). In addition, cross-lagged panel modelling showed that increased optimistic and decreased pessimistic expectancy at week 8 predicted an improved clinical response in patients treated with pharmacotherapy. For CBT, increased optimistic expectancy at pretreatment and decreased pessimistic expectancy at midtreatment predicted greater treatment response.

One key limitation of the study was the low sample size.

“Results suggest that outcome expectancy improved during treatment for depression. Whether outcome expectancy represents a specific mechanism for the reduction of depression warrants further investigation,” the researchers concluded.

Reference

Thiruchselvam T, Dozois DJA, Bagby RM, Lobo DSS, Ravindran LN, Quilty LC. The role of outcome expectancy in therapeutic change across psychotherapy versus pharmacotherapy for depression. J Affect Disord. 2019;251:121-129.