High prevalence of obsessive-compulsive disorder among posttraumatic stress disorder patients.

Posttraumatic obsessions have been reported in a few studies and case series. However, the magnitude of this phenomenon is still unknown. In the current study we systematically evaluated the prevalence of OCD in a sample of combat and terror related PTSD patients. Out of 44 referrals, 43% of the participants had PTSD with no OCD and 41% were diagnosed also with OCD. Six percent had sub-threshold OC symptoms. No difference was found between PTSD and PTSD-OCD participants' characteristics (including demographics, trauma-related factors, and other psychiatric co-morbidity). The surprisingly high number of OCD found in the current study suggests that PTSD-OCD might be underdiagnosed, signifies the importance of direct assessment of OCD in patients with PTSD, and raise questions regarding the underlying mechanism of post-traumatic OCD.