Cannabidiol as a Treatment for PTSD and PTSD Comorbid With TBI

This will be a randomized placebo controlled study to test the efficacy of cannabidiol (CBD) as a treatment for symptoms of post-traumatic stress disorder (PTSD). Subjects, 120 in total, will be males and females with PTSD, half of which will have comorbid mild traumatic brain injury (TBI). There will be three study arms, each with 40 subjects: 1) Oral CBD 400 mg daily; 2) Oral CBD 800 mg daily, and 3) Placebo daily. Treatment duration will be 8 weeks. The primary outcome will be change in PTSD symptoms as measured by change in the Clinician-Administered PTSD Scale (CAPS-5) total score.