Evidence for the cognitive mediational model of cognitive behavioural therapy for depression.
BACKGROUND
Although empirical support for the efficacy of cognitive behavioural therapy (CBT) as a treatment for major depressive disorder (MDD) is well established, its mechanism of action is uncertain. In this investigation, we examined evidence for the cognitive mediational model in a randomized control trial involving CBT, interpersonal therapy (IPT) and pharmacotherapy (PHT) in patients with MDD.


METHODS
One hundred and thirty participants diagnosed with MDD were treated with CBT, IPT or PHT. Participants completed the Hamilton Depression Rating Scale, Beck Depression Inventory-II and Dysfunctional Attitudes Scale prior to and following treatment.


RESULTS
The cognitive mediational model, in which dysfunctional attitudes are proposed to mediate depressive symptom reduction in response to treatment, provided a good fit to the data when contrasting CBT v. IPT, with results supporting a mediational role for dysfunctional attitude change in depressive symptom reduction. The complication model, in which dysfunctional attitudes are proposed to be a consequence of depressive symptom reduction, provided a good fit to the data when contrasting CBT v. PHT, with results supporting a mediational role for depressive symptom reduction in dysfunctional attitude change.


CONCLUSIONS
There was no evidence for a mediational role for dysfunctional attitude change in IPT. Changes in dysfunctional attitudes accompanied both CBT and PHT; however, empirical evidence suggests that the role of attitudes in treatment outcome may differ between these two treatments.
Quilty
L C
LC
Clinical Research Department, Centre for Addiction and Mental Health, Department of Psychiatry, University of Toronto, 250 College Street, Toronto, Ontario, Canada.
McBride
C
C
Bagby
R M
RM
D000328:Adult; D000928:Antidepressive Agents / Q000627:therapeutic use*; D001290:Attitude; D015928:Cognitive Behavioral Therapy / Q000379:methods*; D003131:Combined Modality Therapy; D003469:Culture; D003865:Major Depressive Disorder / Q000175:diagnosis / Q000523:psychology / Q000628:therapy*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008960:Models, Psychological; D009629:Person-Centered Psychotherapy / Q000379:methods; D010555:Personality Inventory; D013813:Therapy, Computer-Assisted / Q000379:methods*
D000928:Antidepressive Agents