Therapeutic emergence of dissociated traumatic memories during psilocybin treatment for anorexia nervosa

Anorexia nervosa (AN) is a severe, often chronic psychiatric disorder with high medical and psychiatric comorbidity and a substantial proportion of treatment resistance. Traumatic histories and related sequelae, including dissociation, commonly co-occur with eating disorders and may contribute to their onset and persistence. The introduction frames psychedelic treatment (PT), particularly agents acting on the serotonin system, as an emerging therapeutic approach with potential relevance to traumarelated conditions and eating disorders because of effects on fear learning, memory, and neural plasticity. This report describes two cases drawn from a 10-person open pilot study of psilocybin-assisted psychotherapy in adults with AN in which previously dissociated traumatic memories surfaced during dosing. The authors set out to present qualitative material about these two participants to illustrate how re-emergent traumatic autobiographical memories — consistent with dissociative amnesia — arose during psilocybin treatment and how their processing related temporally to improvements in eating disorder psychopathology at 3-month follow-up. The paper therefore aims to highlight a phenomenon not previously described in the literature and to discuss possible mechanisms and clinical implications for PT in eating disorders and trauma-related conditions.

This analysis focuses on two of ten female participants enrolled in an open-label pilot study of psilocybin-assisted psychotherapy for AN; the broader study methodology has been reported previously. All participants provided written informed consent and the protocol had regulatory and institutional approvals (FDA, California Regulatory Approval Committee, UC San Diego IRB). Patient names were changed for privacy. Each participant received a single oral 25 mg dose of synthetic psilocybin (COMP360) delivered in the context of psychological support that included preparation sessions, support during dosing, and integration therapy. Two integration sessions were scheduled on Day 1 and Day 7 after dosing, and clinical reassessments occurred at 1 and 3 months. Screening included the MINI International Neuropsychiatric Interview (version 7.0.2) to assess current PTSD among other diagnoses. The data presented here derive from semi-structured qualitative interviews conducted approximately 3 months after dosing; interviews lasted about one hour, were recorded and transcribed, and were carried out by a trained research assistant. Quantitative clinical measures reported for the cases include body mass index (BMI), Eating Disorder Examination (EDE) Global scores as an index of eating disorder psychopathology, and Spielberger State-Trait Anxiety Inventory (STAI) scores where reported. The authors also considered diagnostic criteria for dissociative amnesia (DA) retrospectively in light of the emergent memories.

Two individual case vignettes are reported in detail. Case 1 ("Heather") was a 23-year-old woman with restricting-type AN (BMI 17.6; pre-treatment EDE Global score 2.7) and a past history that included bulimia nervosa, major depressive disorder, generalized anxiety disorder and ADHD. During the psilocybin dosing session she experienced a vivid, spontaneous re-experiencing of a rape that she had previously not recalled clearly. The acute memory retrieval provoked distress and a transient increase in anxiety: reported STAI trait scores rose from 63 to 69 and state scores from 62 to 65 from Day -1 to Day 1, with state anxiety decreasing to 56 by one week. Integration therapy was used to process the memory. Eating disorder psychopathology remained stable at 1 month (EDE 2.7) but declined by 3 months (EDE 1.7), and BMI increased by 0.5 (from 17.6 to 18.1) between 1 and 3 months. Qualitative interview excerpts indicate that Heather regarded the emergence of the memory as enabling identification of root causes and providing material for therapy. Case 2 ("Angela") was a 31-year-old woman with binge-purge AN (BMI 16.9; pre-treatment EDE Global score 4.1) and histories of major depressive disorder and generalized anxiety disorder. She denied salient traumatic events at screening but during the dosing session described accessing ‘‘repressed memories’’ of sexual molestation by a sibling and related family events. Angela characterised the memory retrieval as corrective and therapeutic, reporting that gaining fuller contextual memory allowed her to process anger and derive new meaning; she also described somatic symptom resolution (nausea) concurrent with integration of memory fragments. Quantitatively, her EDE Global score fell sharply to 1.2 at 1 month and 1.0 at 3 months, and BMI rose from 16.9 pre-treatment to 18.1 at 3 months. The authors note that both participants were the only two of ten in the pilot who had histories of binge-purge symptoms, and that neither met criteria for current PTSD on screening interviews yet both retrospectively met criteria for dissociative amnesia given the emergence of previously inaccessible autobiographical traumatic material. Both cases had remitted eating disorder psychopathology by the 3-month assessment, defined by EDE Global scores within one standard deviation of community norms.

Peck and colleagues interpret these two cases as illustrating that psilocybin-assisted psychotherapy can occasion therapeutic emergence and processing of previously dissociated traumatic memories in people with AN, and that such processing may be temporally associated with clinical improvement in eating disorder pathology. The investigators emphasise that, although both experiences were challenging, the participants reported the surfacing and integration of traumatic autobiographical material to be ultimately healing and contributory to recovery at 3 months. The discussion situates these observations within prior literature indicating memory-related effects of classic psychedelics. Earlier reports and clinical-series work have documented recovery or reliving of previously inaccessible memories under psychedelics, and the authors link such observations to plausible neurobiological mechanisms: serotonergic modulation, enhanced synaptic plasticity, changes in default mode network connectivity, facilitation of fear extinction and new learning, and effects that reduce avoidance and increase acceptance, connectedness and empathy. These mechanisms are presented as ways psilocybin might promote retrieval and cognitive–emotional integration of traumatic memories. The authors acknowledge substantial limitations. The findings are based on two cases from a small, open, uncontrolled pilot study and thus cannot support causal claims or generalisability. Participants were not evaluated a priori for lifetime PTSD or dissociative disorders, integration support was limited to two sessions after dosing, and emergent memories were not independently substantiated. The extracted text notes uncertainty about the extent to which memory emergence versus other factors drove improvements in eating disorder symptoms. The possibility of false memory induction under psychedelics is recognised; the authors cite guidance that facilitators should avoid leading, focus clinical support on patient-centred recovery rather than external verification of memories, and gently help participants reflect on adaptiveness when confusion arises. Practically, the investigators recommend systematic trauma screening beyond diagnostic PTSD in future ED psychedelic trials, preparatory informed consent that responsibly advises participants about the possibility of emergent autobiographical material without priming or suggesting therapeutic inevitability, and training for facilitators to manage traumatic content across preparation, dosing and integration phases. They also caution that memory emergence can occasion short-term destabilisation, illustrated by the transient worsening in anxiety and weight loss in Case 1, and stress the ethical obligation to provide adequate post-session support to mitigate medical and psychological risks. Finally, the authors call for larger, controlled studies to evaluate the therapeutic potential of PT for dissociative amnesia, PTSD and trauma-associated eating disorders, while reiterating that these case observations are preliminary and hypothesis-generating.