Stress-induced cortisol reactivity as a predictor of success in treatment for affective dimensions.

•Study evaluates role of cortisol reactivity in predicting psychotherapy outcome.•The study recruited a transdiagnostic sample randomized into two therapies.•Participants underwent intermittent stress induction tasks before treatment.•Average and higher cortisol reactivity predicted faster reductions in symptoms across study.•However, results were not moderated by treatment condition.