MDMA paired with psychotherapy reduces PTSD symptoms more effectively than psychotherapy or medication alone, but how MDMA enhances therapy is unclear. In adult male rats, MDMA given before fear extinction training impaired later recall of cued fear extinction without affecting fear relapse. MDMA given during the reconsolidation phase—but not outside it—produced a delayed and lasting reduction in conditioned fear. These results suggest MDMA may improve psychotherapy by disrupting fear memories during reconsolidation rather than by enhancing extinction.
Ketamine, a dissociative anesthetic and drug of abuse, was tested in adult zebrafish to examine its effects on memory, anxiety, aggression, and stress. A single 20-minute exposure to a high concentration (40 mg/L) caused slight memory impairment in an avoidance task without affecting movement or anxiety. Repeated daily 20-minute exposures for seven days did not alter locomotion, aggression, anxiety-like behavior, or whole-body cortisol levels, but the highest concentration increased circling, a repetitive behavior. The findings suggest that acute ketamine disrupts memory, while repeated exposure may induce stereotyped behaviors without changing stress or social responses.