Therapist interventions and patient outcome: addressing the common versus specific factor debate

While innumerable studies have demonstrated the efficacy of CBT with patients with depression, the mechanisms responsible for depression reduction are not well understood. Aim. This study explored the relationship between therapists’ individual techniques and patients’ symptoms of depression, cognitive errors, and coping. Of particular interest was the relative importance of techniques specific to CBT and those common to all therapies. Method. CBT therapy sessions of 43 patients with major depressive disorder (MDD) were analyzed using observer-rated measures: the Comprehensive Psychotherapeutic Interventions Rating Scale (CPIRS; Trijsburg et al., 2002) for therapist interventions, and the Cognitive Errors Rating Scale (CERS; Drapeau, Perry, & Dunkley, 2008), and Coping Patterns Rating Scale (CPRS; Perry, Drapeau, & Dunkley, 2005) for patients’ cognitive errors and coping strategies. The Beck Depression Inventory (BDI; Beck, Rush, Shaw, & Emery, 1979) was used to assess symptoms of depression. Results. Results of hierarchical multiple regressions, controlling for pre-treatment depression scores and early cognitive errors and coping scores, showed the common factor intervention ‘rapport’ as the only intervention that significantly predicted improvement. Among CBT interventions, only the structuring intervention ‘scheduling and structuring activities’ emerged as a positive predictor of symptoms of depression. Discussion. These results provide further support for the importance of the therapeutic alliance in predicting depression outcome. While the lack of positive results on therapist CBT technique seem to cast doubt on their relative importance, it may also highlight the importance of measuring technique more contextually.