Randomized, Controlled Trial of the Effectiveness of Short-Term Dynamic Psychotherapy and Cognitive Therapy for Cluster C Personality Disorders

Objective: This study compared the effectiveness of short-term dynamic psychotherapy and cognitive therapy for out-patients with cluster C personality disorders. Method: Patients (N=50) who met the criteria for one or more cluster C personality disorders and not for any other personality disorders were randomly assigned to receive 40 weekly sessions of short-term dynamic psychotherapy or cognitive therapy. The most common axis I disorders in the patient group were anxiety and depression diagnoses. Therapists were experienced, full-time clinicians and were receiving manual-guided supervision. Outcome variables included symptom distress, interpersonal problems, and core personality pathology. Measures were administered repeatedly during and after treatment, and change was assessed longitudinally by means of growth modeling procedures. Results: The overall patient group showed, on average, statistically significant improvements on all measures during treatment and also during a 2-year follow-up period. Significant changes in symptom distress after treatment were found for the group of patients who received short-term dynamic psychotherapy but not for the cognitive therapy patients. Despite these differences in intragroup changes, no statistically significant differences between the short-term dynamic psychotherapy group and cognitive therapy group were found on any measure for any time period. Two years after treatment, 54% of the short-term dynamic psychotherapy patients and 42% of the cognitive therapy patients had recovered symptomatically, whereas approximately 40% of the patients in both groups had recovered in terms of interpersonal problems and personality functioning. Conclusions: Both short-term dynamic psychotherapy and cognitive therapy have a place in the treatment of patients with cluster C personality disorders. However, factors other than treatment modality may discriminate better between successful and poor outcomes. Such factors should be explored in future studies.