This is Part 1 in a two-part series about the lack of representation in psychedelic research. This first part explores the history of medical bias that continues to systematically exclude women, minorities, and gender diverse people from clinical trials. Partie 2 explores the structural issues within the medical model and imagines community-based alternatives.
Recent years have seen a global explosion in recherche psychédélique et le développement de traitements, conjugués à des victoires inattendues comme celle du président Trump commande exécutive to expedite the research and review of psychedelic drugs for therapeutic use in April 2026.
De plus en plus de recherches montrent que les psychédéliques ont un immense potentiel en matière de traitement thérapeutique, notamment pour troubles de santé mentale. However, the current direction in which psychedelic R&D is heading leaves us with an important dilemma: with such a highly medicalised model, how can such a groundbreaking transformation happen when key populations who need this treatment most continue to be systematically excluded from clinical trials?
This was the focus of this year’s Conférence internationale sur la recherche psychédélique (ICPR 2026). Focusing on the history of bias in biomedical research, and more specifically on the systematic omission of gender differences in clinical trials, Grace Blest-Hopley – founder of Hystelica, a psychedelic research organisation focusing on the use of psychedelics to understand, treat, and empower women’s health – brought this topic to light in her impactful opening keynote speech titled, “The 51% Blind Spot: Psychedelics, women’s health, and the opportunity we must not miss”.
Répéter les erreurs passées
Le problème de l'exclusion systémique des femmes de la recherche biomédicale n'est pas nouveau. Ce n'est que lorsque 1993 that women and minorities were required to be included in clinical research funded by the National Institute of Health in the US (and 2014 when the European Medicines Agency introduced the Règlement (UE) n° 536/2014 relatif aux essais cliniques).
Les conséquences de cette omission qui a duré des décennies se font encore sentir. De nombreux médicaments prescrits aujourd'hui ont été approuvés par la FDA avant l'instauration de cette exigence, ce qui signifie qu'ils ont été testés principalement sur des sujets masculins blancs, puis que leurs effets ont été généralisés à l'ensemble de la population. Le fait que les femmes subissent des effets indésirables liés aux médicaments est préoccupant. nearly twice as often as men is largely a direct legacy of this history.
Women are disproportionately affected by the very conditions psychedelic-assisted therapy shows the most promise in addressing. Depression affects women at environ deux fois le taux chez les hommes. Les troubles anxieux suivent un modèle similaire, as does PTSD: while the narrative in clinical trials often centres on veterans, women experience PTSD at deux fois plus que les hommes, often due to past abus sexuel or childhood trauma.
When it comes to addiction, women with substance use disorders develop addiction more rapidly after first use, experience higher rates of trauma and gender-based violence, and face greater stigma and structural barriers seeking treatment. There are also conditions that are exclusive or predominant to the female sex: premenstrual dysphoric disorder (PMDD), perinatal depression, and the mental health burden associated with endometrioses, for which psychedelic treatments are only now beginning to be explored, often by organisations operating at the field’s margins precisely because mainstream research has not prioritised them.
The evidence gap
Psychedelic research, despite its progressive reputation, has largely inherited the same structural blind spots as the rest of biomedical science. Current data presented during Blest-Hopley’s keynote highlighted that women make up seulement 18 à 36 % of participants in psychedelic clinical trials – a figure that is particularly shocking given that women bear a disproportionately high burden of the mental health conditions psychedelic treatments are designed to address.
Comme l'a souligné Blest-Hopley dans son discours d'ouverture, les femmes sont aussi statistiquement plus probable to experience adverse reactions during psychedelic trials that current protocols have not been designed to account for, and 50-75% of those adverse reactions go unaccounted for in the existing data.
But just including women won’t solve the issue. Blest-Hopley emphasised a critical distinction during her speech: the issue is not simply that women have been excluded, but that even when they were present in studies, the field failed to look closely at their data. “Many of [the studies] included women, but they did not look into the data that was recorded,” said Blest-Hopely. So even though women are technically present, they remain scientifically invisible as their experiences are overlooked or simply absorbed into a dataset that was not designed with them in mind.
Then there are the questions that few researchers have even thought to ask. For example, psychedelics interact with hormonal systems in ways that current trials have barely begun to investigate. The phase of a woman’s menstrual cycle can affect how a psychedelic is metabolised and experienced, drug sensitivity is generally higher in women, and there is emerging evidence that hormonal contraception can blunt or alter the psychedelic experience altogether. The implications of these gaps for the safety of women using psychedelics, their dosage, and therapeutic outcomes remain largely unknown.
A examen de la portée published in the International Journal of Drug Policy captured the scale of this omission. After analysing 75 studies on the use of psychedelics for substance use disorders spanning more than 60 years, the authors found that only 18 studies had samples that were close to being sex-balanced, nine included no women at all, and not a single study analysed sex or gender differences in its discussion section.
We already knew that there is a grave issue of systemic bias in medical research and funding (for example, erectile dysfunction currently receives five times more funding than researching endometriosis, a condition affecting one in ten women globally). Psychedelic science has arrived into this system, and, so far, it has not found a way out of it.
Minorities and gender diverse people
The representation crisis in psychedelic research does not begin and end with women. A final panel session at the ICPR 2026, “Psychedelics in Context: Gender and sexual diversity, precarity, and power”, made it increasingly clear that these omissions are intersecting and compounding. The further a person is from the white, male default of the clinical trial participant, the less the evidence speaks to their experience.
La chercheuse Sabrina Cluesman a présenté des travaux sur ketamine-assisted group therapy conçu spécifiquement pour traiter les traumatismes liés à l'identité chez les adultes transgenres et de genre non conforme, une population qui vit PTSD at significantly higher rates than the general population, alongside disproportionately high rates of depression, anxiety, and suicidal thoughts – driven largely by discrimination, minority stress, and gender-based violence. They are among those with the highest need for effective mental health intervention, and among those least represented in the research that is supposed to generate it.
For this population, the clinical infrastructure of psychedelic treatment is almost entirely unadapted. As Cluesman pointed out, clinical frameworks typically can’t properly gender these patients, and often lack tools to meaningfully account for abuse history in informed consent processes. And because the psychedelic experience does not happen in a social vacuum, for gender diverse people navigating a world that frequently nie leur identité, encountering another system that cannot acknowledge who they are impacts their therapeutic experience.
The statistics are just as grim when it comes to the exclusion of racial and ethnic minorities and immigrant populations. Recherche from the US found that between 1993 and 2017, 82.3% of psychedelic research participants were non-Latino white. Immigrant and displaced populations are almost entirely absent from the data.
Ronica Mukerjee, an abolitionist, harm reductionist, and one of the most compelling voices at ICPR 2026, noted that only 4.8% of psychedelic studies track immigrant status. This is not incidental. It reflects a research design created for and by a very specific type of person, and one that has struggled to extend beyond it. This systematic exclusion in participants is a reflection of the research centres themselves: 88 % des centres de recherche sur les psychédéliques sont dirigés par des Blancs, et 92 % d'entre eux sont dirigés par des hommes blancs.
« Notre travail n’est pas de faire en sorte que les gens s’intègrent », a déclaré Mukerjee lors de la dernière table ronde de la conférence, consacrée au genre, à la précarité et au pouvoir.
