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Henry Otgaar

Department of Clinical Psychological Science, Faculty of Psychology and Neuroscience, Maastricht University, Maastricht, Netherlands.

3 papers in the library · 6 citations · publishing 2025-2026

Papers

Ayahuasca enhances the formation of hippocampal-dependent episodic memory without impacting false memory susceptibility in experienced ayahuasca users: An observational study.

Journal of psychopharmacology (Oxford, England) April 1, 2025 Manoj K Doss, Lilian Kloft, Natasha L Mason et al. 5 citations

In experienced users, ayahuasca acutely enhances recollection-based memory—the ability to recall specific details—without increasing false memories or affecting familiarity-based memory, a feeling of knowing. In an observational study of 24 Santo Daime members who had consumed ayahuasca over 500 times on average, participants completed a false memory task before and after taking a self-selected church dose. After ayahuasca, hit rates, memory accuracy, and recollection improved, while familiarity and false memory remained unchanged. The authors suggest that β-carboline activity in the brew may account for this recollection enhancement, which contrasts with past psychedelic research showing impaired recollection. Practice effects could not be ruled out, but multiple measures of false memory and metamemory did not improve across sessions.

Questioning the recovery of dissociated traumatic memories under psilocybin: comment on “Therapeutic emergence of dissociated traumatic memories during psilocybin treatment for anorexia nervosa”

Journal of Eating Disorders December 4, 2025 Samuli Kangaslampi, Max Wolff, Manoj K. Doss et al. 1 citation

Psychedelics like psilocybin can trigger vivid memory-like experiences, but a recent case report claiming that two patients recovered dissociated traumatic memories during psilocybin treatment for anorexia nervosa may not have adequately considered alternative explanations. The cases do not necessarily show that psilocybin induces recovery of dissociated traumatic memories or could treat dissociative amnesia. The authors also caution against explicitly preparing patients for the emergence of forgotten material, as such suggestions warrant scrutiny.

Evaluating the evidence for repressed memory recovery in psychedelic contexts

Psychopharmacology April 29, 2026 Anne-Fiona Griesfeller, Lotte Kooman, Lilian Kloft-Heller et al.

A scoping review of 53 sources found no coherent explanation for how psychedelics might recover repressed memories, nor consistent evidence that they do so reliably. Most publications focused on LSD, but few defined what they meant by repressed memory. Proposed mechanisms—psychoanalytical reductions of defensive memory blockades and neurobiological alterations of executive control—lacked empirical support. The review concludes that future work should provide clear definitions, test effects across multiple psychedelic substances, use placebo-controlled designs, and account for the potential occurrence of false memories.