Improved mental health outcomes and normalized spontaneous EEG activity in veterans reporting a history of Traumatic Head Injuries following participation in a psilocybin retreat

Grace Blest-Hopley^1*Giuseppe Pasculli^2,3Simon Gd Ruffell⁴Olateju Emmanuel⁵Kathryn M Pate⁶Hannes Simon Kettner^7,8Leor Roseman⁹Robin Carhart-Harris^7,8

• ¹Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, England, United Kingdom
• ²Department of Computer, Automatic and Management Engineering, Faculty of Information Engineering, Computer Science and Statistics, Sapienza University of Rome, Rome, Italy
• ³Italian Society of Psychedelic Medicine (Societá Italiana di Medicina Psichedelica - SIMePsi), Strada Privata Albergo 5, 70124, Bari, Puglia, Italy, Bari, Italy
• ⁴Social, Therapeutic, and Community Studies, Goldsmiths, University of London, London, United Kingdom
• ⁵Department of Electronic and Electrical Engineering, Obafemi Awolowo University, Ile-Ife, Nigeria
• ⁶Coruna Medical LLC, Longmont, CO, USA, Longmont, United States
• ⁷Centre for Psychedelic Research, Imperial College London, London, England, United Kingdom
• ⁸Psychedelics Division, Neuroscape, University of California, 94143, San Francisco, USA, San Francisco, United States
• ⁹Department of Psychology, University of Exeter, United Kingdom., Exeter, United Kingdom

Psilocybin, a serotonergic psychedelic, has shown therapeutic potential in treating mental health disorders by, amongst the many effects, promoting neuroplasticity and reorganizing functional connectivity across cortical and subcortical networks involved in emotion and cognition. Veterans with traumatic brain injuries (TBI) often experience chronic neurological and psychological symptoms such as post-traumatic stress disorder (PTSD) and depression. This study investigates the effects of psilocybin administered in retreat settings on veterans with a history of TBI, focusing on mental health outcomes and changes in brain connectivity as measured by EEG.A total of 21 participants were recruited through the Heroic Hearts Project, which facilitated access to two six-day psilocybin retreats in Jamaica. Before the retreat, participants underwent three individual and three group coaching sessions to prepare for the experience. During the retreat, two psilocybin ceremonies were held, spaced 48 hours apart. Participants received an initial dose of 1.5g to 3.5g of dried psilocybin mushrooms, with the option to increase the second dose up to 5g. Psilocybin was administered in a tea format, under the supervision of experienced facilitators. Psychological outcomes were assessed using validated questionnaires (PCL-5, PHQ-9, STAI) at baseline (four weeks pre-retreat) and four weeks post-retreat. Electroencephalography (EEG) was used to measure brainwave activity pre- and post-treatment. Paired t-tests were used to analyze changes in psychological scores, while EEG frequency band analysis assessed changes in brain function and connectivity.Improvements were observed across several mental health measures: PTSD (PCL-5 scores decreased by 50%, p=0.010), depression (PHQ-9 scores decreased by 65%, p<0.001), and anxiety (STAI scores decreased by 28%, p<0.001). EEG data showed decreased delta and theta power in frontal and temporal regions, indicating potential improvements in cognitive control and emotional processing. Enhanced coherence in alpha and beta bands suggested improved neural communication.The study suggests that psilocybin retreats might improveme psychological well-being and brain connectivity in veterans with TBI. Reduced delta power and normalized theta activity suggest better emotional regulation, while improved coherence in alpha and beta bands may reflect increased cognitive engagement. These preliminary outcomes provide a rationale for the design and implementation of larger-scale, controlled studies to validate these initial findings.