Comparing the efficacy of group and individual psychological therapy for persistent depression and evaluating effectiveness and change processes in group Cognitive Behavioural Analysis System of Psychotherapy for persistent depression in an outpatient setting
Thomson, Lisa Maree
BACKGROUND: Persistent depression (PDD) is a difficult to treat condition with poor outcomes. There is a growing evidence base for psychological treatment for PDD and it is recommended there is an interpersonal element to therapy. However, much is still to be discovered about the relevant moderating and mediating variables involved in successful treatment. Group psychotherapy is thought to be as effective as individual therapy for Major Depressive Disorder but little is known about any possible advantages in treating PDD. Cognitive Analysis System of Psychotherapy (CBASP) was developed by McCullough (2000) to specifically treat PDD and involves a cognitive, behavioural, psychodynamic and interpersonal approach. Research has shown it to be effective at reducing depression symptoms and increasing interpersonal functioning in both individual and group formats. Interpersonal learning acquisition is measured in CBASP and it is theorised that this precedes symptom improvement as a person learns to apply the skills out-with the therapy room. PURPOSE: A systematic review and meta-analysis sought to compare group and individual psychological therapy to establish if there was any advantage to group therapy in individuals with PDD. An empirical study reviewed the outcome data from 13 groups of CBASP (CBASP-G) which was delivered in an outpatient setting to examine the process of change. Methods. A systematic review of the literature identified randomised controlled trials (RCT) that used psychological therapy for PDD. Twenty studies met the inclusion criteria, and a meta-analysis was performed to compare the effectiveness of group and individual therapy using post mean effect sizes. Studies were checked for risk of bias. Subgroup analyses were used to investigate the impact of moderators such as control type (active or inactive) and depression type (chronic depression or dysthymia). Outcome data from CBASP-G was gathered for the empirical study and extracted and analysed using paired t-tests and multilevel modelling statistical methods. Overall effectiveness, pattern of change of symptoms (overall distress and mood), skill acquisition, interpersonal functioning and global measures of improvement were examined in the analysis. RESULTS: Group psychotherapy was found to have a moderate significant effect compared with a small effect for individual therapy, and the subgroups were significantly different. However, the sample had substantial heterogeneity and moderator analyses found that type of depression, control, and risk of bias were important factors when considering the results. In the empirical study CBASP-G was found to significantly improve depression, distress and mood symptoms. Significant change was found in the hostile-submissive interpersonal domain. Multilevel modelling revealed that skill acquisition improved the model fit significantly, but not all types had a significant result. Change was found to be linear for symptoms and quadratic for skill acquisition. DISCUSSION: The thesis findings give preliminary evidence that psychological treatment for PDD is effective and that there may be an advantage to group delivery. Additionally, it gives some support to McCullough’s (2000) model that CBASP-G is an effective treatment for PDD, and skill acquisition is important in facilitating interpersonal change and symptom improvement. The review indicates that higher quality studies and further research are required to examine the impact of variables and moderators that are likely to have an impact on any differences between group and individual treatment. Longer follow up would help investigate the role of skill acquisition and routine analysis of the current provision of treatment for PDD in community settings is recommended.