Methodological fragmentation and integration priorities in psychedelic-assisted therapy assessment: a scoping review.

INTRODUCTION: Psychedelic-assisted therapy (PAT) is an emerging complex intervention for psychiatric and existential conditions (i.e., forms of distress related to meaning, mortality, and identity, such as that arising in life-threatening illness); however, a systematic characterization of the evaluation methods used across the entire clinical intervention remains incomplete. This scoping review synthesizes the scientific literature on the methodologies and frameworks for evaluating PAT, covering pre-session screening, acute experience, intervention processes, post-session integration, clinical and existential outcomes, safety, and service evaluation. METHODS: Following PRISMA-ScR (Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews) guidelines, we analyzed 59 peer-reviewed publications, comprising contemporary PAT literature published between 2008 and 2026 and foundational psychometric sources for established instruments used in PAT. The findings were categorized into four evaluation domains: (i) assessment instruments for subjective experiences; (ii) clinical intervention models and competency frameworks; (iii) clinical and existential outcome measures; and (iv) safety, ethics, and implementation frameworks. RESULTS: The analysis reveals a number of advances, including the development and cross-cultural adaptation of validated instruments for measuring mystical and challenging experiences. Clinical intervention frameworks emphasizing the importance of the "therapeutic container" have been articulated, and preliminary work has begun to identify core practitioner competencies. PAT has been associated with preliminary findings from controlled studies for conditions such as depression, anxiety, post-traumatic stress disorder, and existential distress, although demographic representation in trials remains limited, and methodological constraints (e.g., small samples and challenges in blinding) warrant cautious interpretation. The review also identifies gaps: methodological integration is still incomplete, with different assessment domains rarely combined into unified protocols; measures for post-session integration and existential outcomes remain undervalidated; and safety monitoring and implementation science present areas requiring standardization. DISCUSSION: This review maps the current methodological landscape, documenting areas of advancement and defining priorities for developing the integrated, multidimensional evaluation models required to advance the field.