The Effectiveness of Intensive Short-Term Dynamic Psychotherapy on Reducing Symptoms and defensive mechanisms of Cluster C Personality Disorders

This study was conducted to investigate the effect of intensive short-term dynamic psychotherapy (ISTDP) on reducing the symptoms and defensive mechanisms of cluster C personality disorders. This study was a quasi-experimental study with a single-subject A-B-A design. The statistical population of this study consisted of all individuals with cluster C personality disorders in Tehran in 2019. Among the above statistical population, 9 individuals who received diagnoses of three dependent, obsessive-compulsive and avoidant personality disorders based on the Millon Clinical Multiaxial Inventory (MCMI-III) and Structured Clinical Interview for DSM Disorders (SCID-II) was selected by purposive sampling method. The instruments used in this study were: Millon Clinical Multiaxial Inventory (Millon, 1977), Defense Style Questionnaire-40 (Andrews, Singh & Bond, 1993) and Structured Clinical Interview for DSM Disorders (First, Gibbon, Spitzer, Williams & Benjamin, 1997). In addition, the ISTDP protocol was applied to the research sample according to the Davanlo (1995, 2000) approach for 15 sessions once a week and each session for one hour. Subjects were assessed after baseline assessment, once every 3 sessions, and after the treatment sessions, 3 follow-up assessments were performed at one-month intervals. Data were analyzed using Friedman test and SPSS software version 24. Findings showed that ISTDP reduced symptoms of cluster C personality disorder. Also, this treatment had a significant effect on the reduction of, immature, neurotic defensive and in increasing use of mature defensive mechanisms (p <0.05).