Why psychedelic-assisted therapy studies in eating disorders risk missing the mark on outcomes: a phenomenological psychopathology perspective.

Psychedelic-assisted therapy (PAT) is an emerging intervention in psychiatry, for which there is preliminary evidence for effectiveness in eating disorders (EDs). The subjective psychedelic experience is considered an important driver of positive outcomes following PAT; however, conventional study design approaches often overlook many of the nuances inherent to the experience. Consequently, considerable information is lost between the first-person account and its scientific interpretation and documentation. Phenomenology-a philosophical and empirical approach to studying lived experience-offers tools to assess and understand the experiential mechanisms of PAT. This commentary advances the case for a phenomenological approach to PAT research in EDs, focusing on key domains of experience that underlie both ED psychopathology and psychedelic experiences, including embodiment, intersubjectivity, affectivity, temporality, spatiality and selfhood. We define and outline these phenomenological domains of EDs and psychedelic experiences and critically examine current measurement approaches. Following, we provide specific research recommendations, including phenomenologically grounded qualitative research and microphenomenology (i.e., the assessment of short-lived, pre-conscious experiences), to more fully capture psychedelic experiences and determine their significance for ED outcomes. The application of phenomenology to the PAT study design may contribute to a better understanding of how individuals experience PAT and generate testable hypotheses to advance psychedelic interventions.