What happens when you try to enroll a patient in a psychedelic trial who cannot consent, cannot report their experience, and cannot complete a self-rated depression scale?
That question sounds hypothetical until you read the new review in Molecular Psychiatry proposing that classical psychedelics, psilocybin, DMT, and related compounds, may have therapeutic utility in disorders of consciousness, including vegetative state and minimally conscious state. The authors propose that the field begin designing trials now, and the clinical and regulatory scaffolding required to do that well is largely undeveloped.
The Mechanism Is Plausible. The Measurement Problem Is Real.
The biological rationale here is stronger than it might first appear. Disorders of consciousness are defined by a breakdown in thalamocortical connectivity and cortical integration, the same neural architecture that psychedelics reorganize in healthy brains. A study published in Nature in August 2026 used fMRI and EEG in 62 healthy adults and found that psilocybin reorganized functional brain connectivity in patterns consistent with restored integration across networks that go quiet in states of low arousal. The overlap with what disorders of consciousness researchers are trying to reverse is not incidental, it is the mechanistic premise of this entire emerging line of inquiry.
But mechanistic plausibility and clinical measurability are different problems entirely. In psychiatry trials, we anchor efficacy to patient-reported outcomes. A PHQ-9 score, a MADRS, a subject’s own account of their inner life. In disorders of consciousness, that instrument does not exist in the same form. The gold-standard behavioral assessment is the JFK Coma Recovery Scale-Revised (CRS-R), a multi-item scale across six subscales — auditory, visual, motor, oromotor/verbal, communication, and arousal, that was designed to assist with differential diagnosis and monitor neurobehavioral function over time. It is a clinician-administered behavioral readout, not a patient report. Using it as a primary endpoint in a psychedelic trial would require regulators and sponsors to accept that any meaningful signal it captures reflects a treatment effect rather than natural recovery trajectory, sedation artifact, or examiner variability. That is not a trivial evidentiary bar.
Having treated thousands of patients with ketamine and guided psilocybin sessions, I know how central subjective experience is to how we understand these medicines working. Patients describe the quality of their altered state. They contextualize it afterward in integration sessions. In a minimally conscious patient, that entire layer of the therapeutic model disappears, and what remains is a neurobiological intervention with a behavioral readout, which actually clarifies what we need to validate before anyone runs a Phase 2 in this population.
What the Psilocybin Pipeline Reveals About Readiness
The broader psychedelic pipeline is advancing quickly, but almost entirely within psychiatric indications where patient-reported outcomes anchor the primary endpoint. COMPASS Pathways’ Phase 3 COMP006 study in treatment-resistant depression enrolled patients whose current depressive episodes had lasted, on average, over three years, with an average of more than six lifetime depressive episodes, a severely ill population, but one fully capable of completing a MADRS. Usona Institute’s uAspire Phase 3 program for major depressive disorder similarly depends on validated self-report instruments as primary endpoints.
The regulatory environment has followed that architecture. The EMA’s updated guideline on depression trials, published March 31, 2025 and effective from September 2025, formalized a European regulatory framework for psychedelics but built it around psychiatric applications with functioning, consenting patients. And the FDA’s August 2024 complete response letter to Lykos Therapeutics for MDMA-assisted PTSD therapy, requesting additional data before approval, reinforced that the agency will not stretch its evidentiary framework to accommodate novel mechanistic arguments without robust, interpretable outcome data. That precedent matters enormously for anyone thinking about a disorders-of-consciousness indication, where the outcome architecture is far less developed than it was even in the MDMA-PTSD program.
A landscape analysis of pre-registered psychedelic clinical trials through 2025 shows the overwhelming concentration of trial activity in Phase 1 and Phase 2, predominantly in psychiatric conditions. The disorders-of-consciousness application would require building outcome validation infrastructure that psychiatric psychedelic trials have been able to borrow from decades of antidepressant research. That borrowing option is not available here.
The Design Questions No Protocol Has Answered
Before a disorders-of-consciousness psychedelic trial becomes feasible, the field needs to resolve three structural problems that go well beyond safety pharmacology.
Consent and surrogate decision-making frameworks for experimental psychedelic administration in non-communicative patients represent genuinely uncharted territory, not just ethically, but operationally. IRBs will need to develop standards for this population that do not currently exist for any scheduled psychedelic compound. Surrogate consent for a treatment whose proposed mechanism involves transient alteration of consciousness in a patient who may have some preserved awareness is a consent challenge unlike anything in current psychiatry trial practice.
The second problem is dosing. In my experience running ketamine therapy programs, what patients report about their subjective experience during a session is one of the most informative signals we have about depth of effect and therapeutic direction. That signal is absent in a minimally conscious patient. Dose selection and titration criteria would need to rely entirely on neuroimaging, EEG, and behavioral markers, requiring prospective validation of those markers as proxies for the subjective phenomena that give clinicians confidence in psychiatric applications.
Third, and most practically: the CRS-R has test-retest variability and is sensitive to the patient’s arousal state at assessment. Any trial using it as a primary endpoint will need a pre-specified assessment protocol rigorous enough to survive a regulatory review that, post-Lykos, is going to scrutinize psychedelic trial conduct more carefully than ever before.
What I am watching for next is whether any research group files an IND for a pilot study in this population before the evidentiary infrastructure catches up, and whether FDA issues any early guidance on acceptable outcome frameworks for psychedelic trials in non-communicative patient populations. That guidance, if it comes, will define what this field actually looks like rather than what it aspires to be.
References
- Molecular Psychiatry, “Psychedelics and disorders of consciousness: a new frontier in neurotherapeutics”
- PMC / Nature, “Psilocybin reorganizes functional brain connectivity (62-participant fMRI/EEG study, August 2026)”
- TBIMS, JFK Coma Recovery Scale-Revised (CRS-R): 23-item neurobehavioral assessment across six subscales
- COMPASS Pathways, Phase 3 COMP006 six-month data in treatment-resistant depression
- BioSpace, Usona Institute uAspire Phase 3 psilocybin trial for major depressive disorder
- PAREA, EMA updated guideline on depression trials with dedicated psychedelics section, March 31, 2025
- AJMC, FDA complete response letter to Lykos Therapeutics for MDMA-assisted PTSD therapy, August 9, 2024
- Uyar A, Forbrich L, Lueken U, Evens R. Landscape analysis of pre-registered clinical trials involving classical psychedelics. Journal of Psychopharmacology, 2025
Dr. Leonardo Vando, MD is Principal Investigator of Psychiatry at Vando Medical Services.
