How specific is cognitive change? A randomized controlled trial comparing brief cognitive and mindfulness interventions for depression

Objective: There is a debate in psychotherapy research as to whether different kinds of psychotherapy work through specific mechanisms of change. Particularly, it is questioned whether cognitive change is specific to cognitive therapy. This study aimed to answer this question by comparing a brief cognitive intervention with an active comparison intervention (i.e., brief mindfulness-based intervention) and by following strict methodological guidelines. Method: 72 currently depressed outpatients were randomized to either cognitive intervention (n = 39) or mindfulness-based intervention (n = 33). Automatic thoughts (negative self-statements, well-being, and self-confidence), dysfunctional attitudes (performance evaluation and approval by others) and depressive symptoms were assessed before and six times during treatment. Within-person and between-person mediation effects were analyzed using multilevel structural equation modeling. Results: There was no difference in cognitive change between the interventions. Negative self-statements and performance evaluations were significant mediators of the within-person effect of time on depressive symptoms, while the three other cognitive variables did not change. Conversely, change in depressive symptoms also mediated within-person cognitive change. Conclusion: Cognitive change seems to be a general rather than a specific mechanism of change. However, the mutual impact of cognitive and depressive change does not support a unidirectional causal model.