An investigation of early sudden gains in cognitive-behavioural therapy for depression : client and within-therapy predictors of change : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Clinical Psychology at Massey University, Auckland, New Zealand
Research into discontinuous change patterns across therapeutic treatment has indicated that clients who experience non-linear change patterns (e.g., „depression spikes‟, „transient worsening‟, and „sudden gains‟) have comparatively better outcomes in therapy (Haas, Hill, Lambert & Morrell, 2002; Hayes, Laurenceau, Feldman, Strauss & Cardaciotto, 2007; Illardi & Craighead, 1994; Thompson, Thompson & Gallagher-Thompson, 1995). The focus of the current study is on the discontinuous change patterns that have been identified as sudden gains, where a client shows a large symptom improvement from session to session of therapy (Tang & DeRubeis, 1999). Research into the phenomena of sudden gains has indicated that they are associated with better outcomes within therapy and post therapy; they may help identify clients who will respond favourably to therapy; and that they may provide further clarification around change mechanisms and processes within therapy. The current study had two aims: (1) to investigate the client factors that may predict sudden gains in Cognitive Behavioural Therapy (CBT) for depression; and (2) to investigate the within-therapy factors that may be associated with sudden gains within CBT for depression.
Through an overarching depression study at the School of Psychology, Massey University, a final sample of 28 clients experiencing their first episode of Major Depression (MDE) were recruited. They participated in 20 free sessions and two follow-up sessions of CBT for depression. Depression severity was measured at every session using the Beck Depression Inventory – Second Edition (BDI-II). Attributional style was measured at six time points using the Attributional Style Questionnaire (ASQ). Homework was measured at up to 18 time points using the Homework Rating Scale – Second Edition (HRS-II) – Client Version. A longitudinal multi level design method was used to analyse the data. 42.9% (n=12) of the clients experienced a sudden gain and these clients experienced a faster rate of improvement in depression severity across treatment. Clients‟ attributional style at intake moderated the relationship between sudden gains and rates of change in depression severity across treatment. No moderating relationship was found with either initial symptom severity or co-morbid status at intake and sudden gains and improvement in therapy. Within therapy variables such as attributional style change and homework beliefs across therapy did have a moderating effect on the relationship between sudden gains and improvement in depression severity across treatment. Clinical considerations and implications for future research are discussed.