PRIDE Psilocybin Trial Screening: Eligibility Gaps in Italy

Most Treatment Seekers Excluded from PRIDE Psilocybin Trial

The PRIDE trial, a multicentre phase II study in Italy comparing psilocybin-assisted therapy with personalized neuromodulation for treatment-resistant depression (TRD), excluded 80% of treatment-seeking candidates at its coordinating site. According to screening data published on October 26, 2026, of 67 individuals who sought enrollment between November 2025 and June 2026, only eight (11.9%) were enrolled and treated, while 54 (80.6%) were excluded and five were preliminarily eligible. The trial is registered under EU CT No. 2024-519844-34-03 in the Clinical Trials Information System (source).

Strict Diagnostic Criteria and Real-World Heterogeneity

The primary mechanism driving this high exclusion rate was the application of strict diagnostic criteria for TRD. Half of the excluded candidates (27 out of 54) did not meet the protocol-defined diagnosis of TRD or had another psychiatric diagnosis. Additional exclusion reasons included age outside the protocol range (18.5%), current suicidal or self-harm ideation (13.0%), and substance use disorder or dependence (9.3%). This pattern demonstrates that real-world treatment-seeking populations are more diagnostically diverse than the narrowly defined cohorts eligible for most psychedelic trials.

Notably, the PRIDE trial's exclusion of individuals with active suicidal ideation or comorbid substance use mirrors common practices in psychiatric research, but may inadvertently omit those most in need of novel interventions. This finding is rarely quantified so precisely in other published psychedelic trials, offering a unique window into the practical challenges of recruitment and the diagnostic landscape of those seeking psychedelic therapy.

Implications for External Validity and Trial Design

The exclusion of a substantial majority of candidates raises concerns about the external validity and generalizability of psychedelic trial results. If trial populations are not representative of the broader clinical population seeking treatment, the efficacy and safety profiles derived from these studies may not translate directly to real-world practice. For researchers, this highlights the need to consider broader inclusion criteria, pragmatic trials, or parallel studies targeting excluded subgroups such as those with comorbidities or suicidal ideation.

For regulators and policymakers, these findings may inform future guidance on trial design and post-approval access. The European Medicines Agency (EMA) and national regulators may look to such data when considering conditional approvals, real-world evidence requirements, or expanded access programs. The PRIDE trial's transparent reporting of screening outcomes may set a precedent for future studies, encouraging more granular public reporting of recruitment and exclusion data.

Risks, Unknowns, and the Path Forward

While the PRIDE screening data clarify the magnitude of the eligibility gap, they do not address treatment response or individualized treatment selection. The risks of broadening inclusion criteria—such as increased adverse events or confounding comorbidities—must be weighed against the benefits of greater generalizability. There is also a risk that expanding eligibility without adequate support structures could expose vulnerable patients to harm.

Moreover, the exclusion of individuals with active suicidality or substance use disorders leaves critical knowledge gaps regarding the safety and efficacy of psilocybin in these high-need populations. Future research may require adaptive trial designs, real-world evidence collection, or focused studies on excluded groups to address these unknowns.

Looking Ahead: Toward Precision and Pragmatism in Psychedelic Trials

The PRIDE trial's screening analysis underscores the tension between scientific rigor and real-world applicability in psychedelic research. As interest in psychedelic-assisted psychotherapy grows, trial designers, regulators, and clinicians must grapple with how best to balance safety, validity, and access. The Italian experience may prompt broader international discussion on how to evolve eligibility criteria and trial methodologies to better reflect the populations most likely to seek—and potentially benefit from—psychedelic therapies.

Byline: Dr. Alessia Romano, MD, PhD, Clinical Research Editor. Reviewed by Dr. Tommaso Ferri, MD, October 28, 2026. We reviewed the PRIDE trial's screening data and regulatory filings as primary sources.