Cannabis, Neuroinflammation, and Suicidal Ideation: A Supplemental Brain Imaging Study

This study will be the first to use brain imaging to explore how cannabis affects the brain and inflammation in U.S. military veterans with PTSD. It builds on an ongoing study testing different combinations of THC and CBD in 200 veterans. In this project, up to 100 veterans will complete brain scans before and after 12 weeks of cannabis administration to see how the brain changes over time. The scans will measure a marker sensitive to neuroinflammatory state, brain communication, and activity during thinking and emotion tasks. By linking these brain changes to improvements in PTSD symptoms, suicidal thoughts, and quality of life, this study may help identify which veterans benefit most from cannabis-based treatments and support more personalized care for PTSD.

Inclusion Criteria: * Eligible for, and provided written informed consent to participate in, the Parent Study (NCT06381180) and to be contacted regarding 'future research studies.' * Able/willing to provide written informed consent to participate in the Neuroimaging Study. Exclusion Criteria (eligible if the subject does not meet both criteria): * Contraindications for MRI scanning include, but are not limited to: as braces, pacemaker, implanted metal (self-report MR screening form and ferromagnetic detectors) or medical conditions that prevent comfortable MRI scanning procedures, e.g., inability to lay supine for 60 minutes, claustrophobia, or body weight \> 275lbs. * Contraindications for PET \[18F\]FETrp imaging include, but are not limited to: chronic medical conditions that alter radiotracer pharmacokinetic properties, e.g, Diabetes I/II (or uncontrolled glucose levels \[\>200mg/dl non-fasting\]), abnormal BMI (\ 35kg/m2), autoimmune diseases, or other chronic inflammatory conditions, or take medications (3+ days/week) that will alter radiotracer binding, e.g., glucose stabilizing medications, proton-pump inhibitors, or anti-inflammatory agents, or have medical conditions that prevent comfortable PET scanning procedures, e.g., inability to lay supine for \~75 minutes, tolerate a radial vein catheter and up to 35ml of whole blood drawn, or body weight \> 275lbs.