Treatment of Paranoid Personality Disorder with Cognitive Analytic Therapy: A Mixed Methods Single Case Experimental Design

Paranoid personality disorder (PPD) presents as chronic and widespread interpersonal distrust, whereby the actions of others are interpreted as malevolent and malicious. This research details the assessment, formulation and treatment of a case of PPD within a 24-session contract of cognitive analytic therapy (CAT). The outcome methodology was an A/B with extended follow-up single case experimental design (SCED). The SCED was supplemented with qualitative patient interviewing via the Change Interview regarding their experience of CAT, whether change had taken place and detailing of any identified change mechanisms. Quantitative results show that five out of the six daily rated paranoia target complaint measures were extinguished during the treatment phase. Qualitatively, the patient attributed change to the therapy conducted. The results suggest that CAT was an effective intervention in this case of PPD and are discussed in terms of identified methodological shortcomings, treatment implications and the potential for generating a convincing evidence base for the psychotherapy of PPD. Copyright (c) 2013 John Wiley & Sons, Ltd.