Intravenous ketamine administered in a supportive environment with preparation, intention-setting, integration sessions, eye shades, and evocative music—paralleling psychedelic therapy—was associated with large reductions in PTSD symptoms. In a retrospective sample of 117 outpatients, mean PCL-5 scores dropped from 52.54 to 28.78, with 75% showing clinically meaningful improvement and 62% suggesting remission. No serious adverse events occurred, and concomitant psychotherapy was a significant moderator. The findings suggest that environmental factors may account for variation in previous ketamine studies and that this approach may be a promising option for PTSD unresponsive to other treatments.
A systematic review and individual participant data meta-analysis of 12 studies (533 participants) found that higher baseline PTSD severity was the most robust predictor of symptom reduction after combined ketamine and psychotherapy. More psychotherapy sessions, more ketamine sessions, and shorter treatment duration were also associated with greater improvement, but these findings are tentative because most studies were of poor quality. The analysis showed that for each additional psychotherapy session, PTSD symptoms improved by an average of 1.03 points on the PCL-5, and for each additional ketamine session, improvement was 1.15 points. The results require confirmation in well-designed prospective trials.