Does Cognitive Behavioural Analysis system of psychotherapy improve interpersonal functioning in patients affected by persistent depression and what can research tell us about the theoretical model this therapy is based on?
Background. Cognitive Behavioural Analysis System of Psychotherapy (CBASP) has been developed to treat individuals affected by persistent depressive disorder (PDD). There is a growing number of empirical studies to suggest that CBASP is effective in treating chronically depressed population. Taking into account these findings as well as the chronic and debilitating nature of persistent depression, it can be invaluable, when planning treatment, to understand the factors contributing to and maintaining this condition, as well as mechanisms of change involved in CBASP. Purpose. A systematic review aimed to establish the quality of evidence indicating the effectiveness of CBASP when addressing difficulties with interpersonal functioning which are believed to be causing and maintaining depressive symptoms according to the theory of persistent depression developed by McCullough (2000). McCullough hypothesised that childhood trauma leads to an impairment in the cognitive-emotional development, which then leads to interpersonal difficulties that result in depressive symptoms. An empirical study aimed to identify the strength of the relationships between different constructs in the theoretical foundations of CBASP. Methods. A systematic literature search was conducted identifying research reporting the effects of CBASP intervention on interpersonal functioning in the clinical samples affected by PDD or depression of chronic nature but not meeting all the criteria for PDD. The search yielded nine papers which met inclusion and exclusion criteria. The Effective Public Health Practice Project quality assessment tool was employed to assess the quality of the included studies. In order to collect data for empirical study, a cross-sectional design was used. Clinicians working in the mental health teams in the local board were asked to identify adult patients on their caseloads who were affected by PDD. The clinicians were then invited to introduce the study to these patients and, if the patient showed an interest, offer them a questionnaire pack to read at home. Thirty-two patients with PDD completed and returned a set of questionnaires measuring childhood trauma, pre-operational functioning/reflective functioning, interpersonal difficulties, and depressive symptoms. A series of multiple regression analyses were used to analyse the results. Results. The systematic review provided evidence supporting the hypothesis that CBASP intervention leads to an improvement in the area of interpersonal functioning. The majority of the assessed studies demonstrated the improvements on the measures of interpersonal functioning, while all of the studies showed reductions in depressive symptoms. The methodological quality of the studies has been evaluated to be of good or very good standard which strengthened the reliability and validity of the results. Findings from the empirical study, somewhat surprisingly, failed to demonstrate the hypothesised association between childhood trauma, pre-operational thinking, interpersonal difficulties and the severity of depression. Childhood adversity, pre-operational thinking and interpersonal difficulties did not predict the severity of depressive symptoms. The relationship between childhood trauma and interpersonal functioning, as well as interpersonal functioning and depression, did not reach statistical significance, even when the subscale of the Inventory of Interpersonal Problems (Horowitz, Alden, Wiggins, & Pincus, 2000) measuring a hostile submissive interpersonal style associated with persistent depression, was entered into the model. Discussion. The findings from the first chapter of this thesis provide evidence suggesting that CBASP intervention leads to an improvement in the area of interpersonal functioning and reduction in depressive symptomatology. Importantly, the review's results demonstrated that while the assessed studies were primarily of good quality, more studies investigating specific mechanisms of change involved in the CBASP intervention are needed. The analyses which were part of the empirical study revealed the lack of associations between the constructs used by McCullough in his theory of persistent depression. While it is possible that the relationships between the discussed constructs are weaker than previously established, there have been a number of methodological limitations, such as a potentially unrepresentative sample and its small size, which might have contributed to the absence of predicted effects.