Case analysis of long-term negative psychological responses to psychedelics
Authors: Bremler Rebecka , Katati Nancy , Shergill Parvinder , Erritzoe David , Carhart-Harris Robin L. 
Published: September 2023

Recent controversies have arisen regarding claims of uncritical positive regard and hype surrounding psychedelic drugs and their therapeutic potential. Criticisms have included that study designs and reporting styles bias positive over negative outcomes. The present study was motivated by a desire to address this alleged bias by intentionally focusing exclusively on negative outcomes, defined as self-perceived ‘negative’ psychological responses lasting for at least 72 h after psychedelic use. A strong justification for this selective focus was that it might improve our ability to capture otherwise missed cases of negative response, enabling us to validate their existence and better examine their nature, as well as possible causes, which could inspire risk-mitigation strategies. Via advertisements posted on social media, individuals were recruited who reported experiencing negative psychological responses to psychedelics (defined as classic psychedelics plus MDMA) lasting for greater than 72 h since using. Volunteers were directed to an online questionnaire requiring quantitative and qualitative input. A key second phase of this study involved reviewing all of the submitted cases, identifying the most severe—e.g., where new psychiatric diagnoses were made or pre-existing symptoms made worse post psychedelic-use—and inviting these individuals to participate in a semi-structured interview with two members of our research team, during which participant experiences and backgrounds were examined in greater depth. Based on the content of these interviews, a brief summary of each case was compiled, and an explorative thematic analysis was used to identify salient and consistent themes and infer common causes. 32 individuals fully completed an onboarding questionnaire (56% male, 53% < age 25); 37.5% of completers had a psychiatric diagnosis that emerged after their psychedelic experience, and anxiety symptoms arose or worsened in 87%. Twenty of the seemingly severer cases were invited to be interviewed; of these, 15 accepted an in-depth interview that lasted on average 60 min. This sample was 40% male, mean age = 31 ± 7. Five of the 15 (i.e., 33%) reported receiving new psychiatric diagnoses after psychedelic-use and all fifteen reported the occurrence or worsening of psychiatric symptoms post use, with a predominance of anxiety symptoms (93%). Distilling the content of the interviews suggested the following potential causal factors: unsafe or complex environments during or surrounding the experience, unpleasant acute experiences (classic psychedelics), prior psychological vulnerabilities, high- or unknown drug quantities and young age. The current exploratory findings corroborate the reality of mental health iatrogenesis via psychedelic-use but due to design limitations and sample size, cannot be used to infer on its prevalence. Based on interview reports, we can infer a common, albeit multifaceted, causal mechanism, namely the combining of a pro-plasticity drug—that was often ‘over-dosed’—with adverse contextual conditions and/or special psychological vulnerability—either by young age or significant psychiatric history. Results should be interpreted with caution due to the small sample size and selective sample and study focus.