Cannabinoid 1 receptor availability in posttraumatic stress disorder: A positron emission tomography study

The endocannabinoid system (ECS) plays a critical role in fear learning and maintenance and may, therefore, be implicated in the pathophysiology of posttraumatic stress disorder (PTSD). The exact role of cannabinoid receptor 1 (CB1R), a key component of the ECS, remains unclear. Although preclinical studies largely suggest CB1R downregulation in PTSD, the only prior study of CB1R availability in individuals with PTSD reported higher levels than in controls. In this study, we investigated the relationship between CB1R availability and PTSD diagnosis and symptoms. Using positron emission tomography (PET) with the CB1R-specific radiotracer [¹¹C]OMAR, scans from 62 individuals, including 46 trauma-exposed participants (19 with current PTSD) and 16 healthy controls, were analyzed. Our findings revealed no differences in CB1R availability between groups in either the whole brain or regions of interest. However, emotional numbing symptoms of PTSD were significantly linked to CB1R availability. These results suggest that the ECS role in the maintenance of PTSD is more nuanced than previously suggested. The ECS was linked to specific PTSD symptom expression, highlighting the potential for treatments targeting the ECS in mitigating these specific symptoms of this multi-faceted disorder.