Systematic Review Reveals Major Gaps in PAP Implementation Research

Systematic Review Confirms Lack of Real-World PAP Implementation Research

A systematic review published on November 2, 2026, in OpenAlex (W7225122656) confirms that research on the real-world implementation of psychedelic-assisted psychotherapy (PAP) is significantly lacking. While clinical trials have produced promising efficacy data for PAP in conditions such as posttraumatic stress disorder (PTSD) and depression, this review reveals that only 20 studies to date have addressed implementation in actual clinical settings. The review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA 2020) guidelines and focused exclusively on peer-reviewed research reporting on implementation factors.

Mechanisms and Context: What the Review Found

The review's methodology involved screening 2,406 articles, with only 20 meeting criteria for inclusion—demonstrating the scarcity of implementation-focused literature. Most included studies (15 of 20) used cross-sectional surveys or qualitative interviews to assess organizational perspectives, such as readiness, barriers, and attitudes toward PAP adoption. Only five studies addressed patient perspectives, infrastructure needs, or specific patient characteristics influencing implementation. Notably, the review applied the Practical, Robust Implementation and Sustainability Model (PRISM) to extract data on factors like organizational capacity, training requirements, and sustainability challenges.

This evidence gap is particularly striking given the rapid growth of efficacy trials and the increasing interest from U.S. agencies, including the Food and Drug Administration (FDA), in evaluating PAP for potential approval. The lack of implementation research means that critical questions about how to safely, effectively, and equitably deliver PAP in diverse clinical environments remain unanswered. For example, the review found almost no studies addressing how community mental health settings, rural clinics, or under-resourced providers might adapt PAP protocols developed in academic centers.

Policy and Research Implications: Bridging the Science-to-Practice Divide

The shortage of implementation research poses significant challenges for policymakers, regulators, and health systems preparing for the possible mainstreaming of PAP. Without robust evidence on best practices for training, infrastructure, and patient selection, regulatory agencies may struggle to develop clear guidance or enforceable standards for PAP delivery. This gap also complicates reimbursement decisions by payers and the development of scalable clinical models by industry stakeholders.

Implementation science—distinct from efficacy research—focuses on translating interventions into routine practice. The review highlights the urgent need for dedicated funding streams, interdisciplinary research teams, and partnerships with frontline providers to generate the data necessary for safe scale-up. For instance, the absence of studies on workforce training or supervision models could lead to inconsistent or unsafe delivery if PAP is rapidly adopted without adequate support systems.

Risks, Unknowns, and Failure Modes in PAP Implementation

The lack of implementation-focused evidence introduces real risks for patients, providers, and the broader mental health system. Without clear protocols and validated delivery models, early adopters may face challenges such as inadequate therapist preparation, insufficient integration support, or inappropriate patient selection. These risks are amplified in non-academic settings, where resources and oversight may be limited.

One non-obvious failure mode identified in the review is the potential for inequitable access: most existing implementation studies focus on large, urban, or academic centers, leaving rural and marginalized populations underrepresented. This could result in a two-tier system where only certain groups benefit from PAP, undermining public health goals and potentially fueling legal or ethical challenges.

Looking Forward: Priorities for Implementation Science in PAP

To move from evidence to practice, the field must prioritize research that addresses the practical realities of delivering PAP outside of clinical trials. Key priorities include developing standardized training and supervision models, evaluating infrastructure needs across diverse settings, and studying patient outcomes in real-world contexts. Collaboration between regulators, academic researchers, community providers, and patient advocates will be essential to ensure that PAP can be implemented safely, effectively, and equitably as regulatory pathways evolve.

As the field advances, stakeholders should be cautious not to conflate clinical trial efficacy with readiness for widespread adoption. The review’s findings serve as a call to action for funders, policymakers, and industry leaders to invest in the science of implementation—without which the promise of PAP may remain unrealized for most patients.

By Dr. Alex Greene, PhD, Clinical Implementation Science Editor. How we research: Reviewed by Dr. Alex Greene on 2026-11-03. Sources include the original systematic review (OpenAlex W7225122656) and FDA public guidance documents.