Skill Use Mediates the Within-Person Effect of the Alliance on Session-to-Session Changes in Anxiety and Depression in the Unified Protocol.

Objective: Both the therapeutic alliance and the specific skills taught in treatment are thought to contribute to change in cognitive-behavior therapy (CBT), but it is unclear if or how these processes influence each other and outcomes in treatment. We tested the hypothesis that the degree to which patients used CBT skills would mediate the relation between the alliance and session-to-session changes in anxiety and depression.

Method: Adult participants ( = 70; = 33.74, 67% female, 70% White) with emotional disorders were randomized to receive 6 or 12 sessions of the Unified Protocol. Before each session, participants reported anxiety and depression severity and past-week skillfulness. After each session, participants rated the strength of the alliance. We tested whether greater within-person skillfulness mediated the relation between within-person alliance strength and session-to-session changes in anxiety and depression.

Results: Skillfulness significantly mediated the effect of the alliance on session-to-session changes in anxiety, = -.02, = .04, and depression, = -.02, = .02, such that a stronger alliance predicted greater next-session skillfulness, which predicted session-to-session decreases in anxiety and depression. When alliance subscales were examined separately, the strongest effect was observed for agreement on therapy tasks.

Conclusions: Improvements in the alliance may facilitate skill use and indirectly predict reductions in anxiety and depression through skill use in CBT. We encourage research on how to enhance both the alliance and skillfulness in CBT.