ABSTRACT
BACKGROUND: Assessment and treatment of cohabiting monozygotic (MZ) twins with obsessive compulsive disorder (OCD) is a possible challenge for clinical psychologists. AIMS: This study aims to present a detailed history of two sets of cohabiting MZ twins with OCD, and describe the adaption of cognitive behavior therapy in their treatments. METHOD: Two sets of cohabiting MZ twins completed a structured intake and the Yale Brown Obsessive Compulsive Scale as well as measures of depression, anxiety, a measure of obsessive beliefs, and thought action fusion. One set received cognitive behavior therapy and exposure with ritual prevention (ERP) simultaneously and the other received ERP separately. Pre-, post-treatment and follow-up assessments occurred for both sets of twins. RESULTS: All four individuals showed notable decreases in OCD, and results were maintained for three of the four participants at follow-up points. CONCLUSIONS: This study highlights the developmental course of OCD that can occur in cohabiting twins, and the clinical adaption that may be necessary.
