<p>Abstract: Recent research has focused on how psychedelics and empathogens may assist in the treatment of PTSD and depression following trauma. However, there is almost no knowledge regarding how psychoactive substances may impact the processing of Traumatic Events (TE) in real time. The large-scale terror attack by Hamas on October 7th 2023 on the 4000 attendees of the Supernova music festival has provided a tragic opportunity to study these two phenomena in conjunction. The attack took place shortly after sunrise, when many attendees were under the influence of mind-altering substances, mostly MDMA, LSD, ketamine and, as well as cannabis. This is an unprecedented mass trauma event that many of its victims experienced while in altered states of consciousness. We have begun a large-scale, longitudinal study with these survivors regarding the processing of trauma under the influence of psychedelics in the peritraumatic and post traumatic periods. Our results indicate that approximately 65% of the participants were exposed to severe trauma while under the influence of mind-altering substances. In this talk I will show preliminary results from this unique cohort including clinical (n = 1400), physiological (n = 300), cognitive (n = 900) and neural (fMRI) measures (n = 140) and how they relate to trauma and psychedelic use. The data and experiences of the courageous survivors of the festival provide novel insights into how trauma processing is impacted by psychoactive substances revealing unique interactions between cognitive, pharmacological and clinical factors.</p>