What does the evidence say about cannabis for PTSD?

PTSD is one of the most biologically plausible indications for cannabis, and the evidence is more promising than for most conditions — though still limited by study quality. The ECS rationale: PTSD patients show reduced CB1 receptor availability in the amygdala and anterior cingulate cortex, and lower anandamide levels — suggesting endocannabinoid deficiency in fear-processing circuits. THC may reduce nightmare frequency and severity by suppressing REM sleep and reducing amygdala hyperreactivity. A 2021 Canadian RCT (Jetly et al.) found nabilone (synthetic THC) significantly reduced nightmares vs. placebo. Observational studies consistently show patient-reported improvements in sleep, hyperarousal, and anxiety. However, concerns include: cannabis may impair fear extinction learning (critical for trauma therapy), may worsen dissociation in some patients, and long-term use carries addiction risk. Current evidence supports cautious use for nightmare reduction, not as a replacement for evidence-based psychotherapy.