The relationship between case conceptualization and homework in cognitive behavioural therapy (CBT) for depression : a thesis in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Psychology at Massey University, Albany, New Zealand

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Massey University
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Comprehensive case conceptualization is central to Cognitive Behavioural Therapy (CBT; A. T. Beck, Rush, Shaw, & Emery, 1979). Despite the importance attributed to case conceptualization there is limited empirical support for the utility of case conceptualization in CBT. In particular, there is limited research on the relationship between therapist competence in case conceptualization, in-session and between session treatment planning (i.e., homework), and outcomes. Furthermore, little is known about the evolution of case conceptualization over a course of CBT. In order to facilitate the empirical investigation of case conceptualization in CBT the primary aim of the current thesis was to develop a new method for evaluating case conceptualization, the Conceptualization Rating Scale (CRS; Easden & Kazantzis, 2008; 2009). Study 1 investigated how patients’ (n =10) written case conceptualizations change over a course of CBT for depression using 53 J. Beck Case Conceptualization Diagrams (J. Beck, 1995). Therapist’s resultant case conceptualizations became more complete over the course of therapy with an average of 33% more information being recorded in case conceptualizations from intake to session 10. Consistent with cognitive-behavioural theory, therapists tended to conceptualize core beliefs about the ‘self’ with relatively minimal reporting of beliefs about the ‘world / others’ and the ‘future’. Study 2 provided the training, development and preliminary psychometrics of the CRS. Independent observers (N = 4) rated 225 DVD recorded therapy sessions. The CRS was demonstrated to possess adequate internal consistency (α = .61) and excellent total scale interrater reliability for each of the four domains integration (k = .83), importance (k = .65), competence (ICC = .93), and fit / match (ICC = .86). Results revealed that independent observers were able to agree on different aspects of CBT therapist’s utilization of case conceptualizations during therapy sessions. In Study 3, using the total sample of 28 patients, therapist’s (N = 7) levels of competence were assessed by independent observers (N = 4) using the CRS based on 225 DVD recorded therapy sessions. A multilevel modelling (MLM) analysis revealed that after controlling for time, taken together, therapist competence in homework use and therapist competence in case conceptualization explained 40% of within patient variance and 19% of between patient variance associated with positive change on the BDI-II after controlling for patient beliefs about homework, symptom severity and personality beliefs. The results from each study contribute towards an understanding of the relationship between different domains of therapist competence and outcomes in psychotherapy. More specifically, empirical support is provided for the utility and systematic integration of case conceptualization in CBT for depression. Implications are discussed for supervision, training and clinical practice in CBT to ensure positive patient outcomes and evidenced-based interventions in CBT.
Cognitive Behaviour Therapy, Depression, Case conceptualisation, Homework, Cognitive Behaviour Therapy, Cognitive therapy