ICPR 2025: European Psychedelic Research Confronts Negative Trials, Ethical Breaches, and the Challenge of Inclusivity
Key Insights
The 7th Interdisciplinary Conference on Psychedelic Research (ICPR) in Haarlem highlighted Europe's "moderate temperament" toward psychedelics, contrasting with U.S. financial and political pressures.
A dedicated symposium on negative clinical trials featured a ketamine study for suicidality (search) that found no difference versus midazolam, and the EPIsoDe psilocybin trial for treatment-resistant depression (search) that missed its primary endpoint.
An on-stage interview with Garik Rober, imprisoned for negligent homicide after two deaths during an illegal psychedelic session, raised unresolved questions about therapist training and personal drug use.
The 7th Interdisciplinary Conference on Psychedelic Research (ICPR), organized by the OPEN Foundation (search) and held at the Philharmonie Haarlem in the Netherlands, offered a distinctly European counterpoint to the U.S.-dominated psychedelic discourse. Across three days, researchers, clinicians, and scholars grappled with negative trial results, ethical failures, patient experiences, and the field's growing pains — all framed by what OPEN Foundation executive director Joost Breeksema called a "certain moderate temperament."
"At the risk of generalizing, I think that Europe has approached this field with a certain moderate temperament," Breeksema said during the opening talk. "So much of the discourse is driven by financial pressure, political volatility, opportunism, pharmaceutical companies, deep pockets, celebrities, influencers, tech bros looking for immortality. Our sober outlook looks a little bit more like a sign of maturity."
Breeksema offered a developmental metaphor for the field's current state. "In some ways, I think we're somewhere in the middle of adolescence," he said. "The field is growing fast, faster than many of us anticipated, or were even ready for. We are still trying to figure out what kind of adults we will grow to be."
Negative Trials Take Center Stage
In a symposium titled "Negative clinical trials in psychedelic research: Lessons learned and future recommendations," three researchers presented findings that challenged prevailing optimism about psychedelic therapies.
Jurriaan Strous, a Dutch psychiatrist at the University Medical Center Groningen, detailed a ketamine trial for suicidality (search) that was halted early after enrolling 54 patients when a safety monitoring board deemed it unethical to continue — there was no discernible effect. The study compared ketamine to midazolam, a benzodiazepine. "You see no difference whatsoever," Strous said, displaying graphs of participant scores on the Beck Suicidal Ideation Scale. Notably, when researchers tested for blinding, the number of participants who correctly guessed their group assignment was no better than chance, suggesting successful concealment — a persistent challenge in psychedelic research.
Strous acknowledged his own shift in perspective: "I started off as a real believer back in 2014," but after this study, "I was able to get a more neutral stance towards ketamine."
Psychotherapist Lea Mertens presented the EPIsoDe study, a randomized clinical trial of psilocybin for treatment-resistant depression (search) that failed to meet its primary endpoint of a 50% reduction on the Hamilton Depression Rating Scale. Yet long-term follow-up revealed some participants still experienced depression reduction. Mertens noted that Compass Pathways' Phase 3 trials had similar results but used a different predetermined endpoint and were consequently deemed positive. "It might be a bit too simple to declare a study positive or negative based on one P-value," she said.
During the Q&A, some audience members pushed back on the ketamine findings, with one psychologist questioning whether midazolam's anti-anxiety effects could have masked ketamine's therapeutic benefit. Strous acknowledged the possibility but noted that research on midazolam for suicidality (search) remains scant.
A Harrowing Ethical Reckoning
One of the conference's most striking sessions was an on-stage interview between Garik Rober, a former German physician and psychotherapist, and Peter Gasser, a past president of the Swiss Medical Society for Psycholytic Therapy.
In 2009, Rober led an illegal group psychedelic session in which two people died. He explained that before the session, he took 30 to 40 micrograms of LSD — slightly above a typical microdose — believing it would "open" him to better manage tensions among participants. The group took methylone, then MDMA. Rober, struggling to read the scale while measuring MDMA powder, accidentally administered ten times the intended dose to each person. When participants showed agitation and distress, he gave one man diazepam; minutes later, the man turned blue. Despite CPR, the man died, as did another young participant. Rober was jailed that same day, ultimately convicted of negligent homicide, and served three years in prison with a lifetime ban on practicing medicine or therapy.
The interview, intended as a cautionary lesson, left significant questions unaddressed: why Rober believed LSD would enhance his facilitation capacity, whether such thinking persists in psychedelic circles, and how his training under controversial therapist Samuel Widmer — whose Kirschblütengemeinschaft community faced allegations of cult-like dynamics, sexual abuse, and overdose deaths — may have influenced his decision-making.
During the Q&A, an audience member asked Rober whether his own drug use led to "erroneous ideas" and "narcissism." Rober acknowledged his psychedelic use supported his views at the time, emphasizing the importance of "supervision, intervention, being in contact with colleagues, and being honest." Gasser added, "I think we have to differentiate between taking psychedelics while being in the treatment of patients or taking it outside in a special setting for your training and self exploration. I mean, here it was clear LSD does not help managing any tools." The questioner raised their voice in response: "They both have risks!"
Patient Voices and Postpartum Depression (search)
University of South Florida epidemiologist Amanda Elmore presented findings from interviews with seven participants from a postpartum depression (search) trial sponsored by Reunion (search), investigating RE104 — a novel compound similar to psilocybin but with a shorter trip duration.
All participants who received the active higher dose experienced remission in their depression, reporting they felt more present with their babies and that their confidence as mothers improved. Notably, the women did not raise concerns about having to stop breastfeeding during the study, though they expressed a desire for more post-trial counseling and support.
The range of drug experiences was striking. Some had positive experiences, while others described distress: "My brain was just splitting open… I was so angry during it… very chaotic… not a moment of it was pleasant." Yet both types of experiences could still lead to good outcomes. One participant in the low-dose placebo group also achieved similar remission levels, while another who recognized she was in the low-dose group struggled with disappointment: "I'm back at square one… if I didn't have the treatment then it's like well what now? Where do I go? What do I do?"
European Ketamine Clinics: A Divergent Model
A panel titled "A decade of clinical Insights: real-world evidence from European ketamine clinics" revealed stark differences between European and U.S. practices. Clinicians from the Czech Republic, Germany, Norway, and the Netherlands described ketamine embedded within rigorous therapy programs incorporating art therapy, music, and even kayaking.
"I can't imagine giving ketamine to people… to just leave people in a room," said Rutger Engels, professor of Developmental Psychopathology at Erasmus University Rotterdam and co-founder of the Senz clinic in the Netherlands. Each expert noted that most or all of their clinics were covered by insurance, often through state-funded healthcare. In Norway, the Axon clinic uses an Acceptance and Commitment Therapy-based approach with generic ketamine, for which the country has approved nationwide reimbursement for treatment-resistant depression (search).
Consent, Capacity, and the Boundaries of Psychedelic Therapy
Caroline Hayes, a psychiatrist based in Newcastle-upon-Tyne, UK, addressed the provocative question of whether psychedelics could ever be given in clinical settings to patients lacking capacity to consent. She referenced a 2025 case report in which a woman in a minimally conscious state received psilocybin. "This made me feel a little bit uncomfortable," Hayes said.
Her central argument: the research is not sufficiently advanced to justify such administration. Patients with disorders of consciousness cannot communicate if an experience is challenging, and they cannot receive preparation or integration support. Hayes extended her caution to dementia cases, despite anecdotal reports of temporary functional gains. When an audience member suggested prior consent mechanisms similar to those used for euthanasia in the Netherlands, Hayes remained wary: "Your opinion might change, you know, the version of you that signed that form isn't the version of you that is experiencing that later stage."
Inclusivity and the Crystallizing Field
The closing session brought unscripted reflections from a randomly selected group of speakers. Adana Omagua Kambeba, an Indigenous Brazilian medical doctor, noted that at ICPR two years ago there was only one Indigenous representative; this year there were five. "The vast majority are scientists, researchers, and people connected to pharmaceuticals, but where are the guardians of these medicines that here are called psychedelics?"
Grace Blest-Hopley, whose keynote addressed the neglect of women's health in psychedelic research, called for sustained focus on sex-based biological variables. Sociologist Joanna Kempner highlighted the cluster headache community, sometimes marginalized because members seek pain relief rather than the psychedelic experience itself. Josh Hardman of Psychedelic Alpha noted that as medical psychedelics become more available, the need for patient representation will only increase.
Anthropologist Manvir Singh offered a reflective note on the field's maturation: "How can psychedelics continue to benefit from interdisciplinarity and new ideas flowing in, while not being subject to the limitations that come as a field develops, which can close it off from other conversations?"
The conference, with its pervasive critical slant — panels on negative results, erotic feelings in therapy, psilocybin non-responders, and the limitations of diagnostic categories — embodied what one attendee described over coffee as being "neither too optimistic nor too pessimistic." It was, as Breeksema might say, a sign of a field learning to grow up.