Authors: Elena Koning, Riccardo Miceli McMillan, Aaron Keshen, Phillipa Hay, Anthony Vincent Fernandez, Jack Reynolds, Stephen Touyz
Categories: Comment, Eating disorders, Psychedelics, Psychedelic-Assisted therapy, Phenomenology, Experience, Study design
Source: Journal of Eating Disorders
Authors: Elena Koning, Riccardo Miceli McMillan, Aaron Keshen, Phillipa Hay, Anthony Vincent Fernandez, Jack Reynolds, Stephen Touyz
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.
Psychedelic-assisted therapy (PAT) is emerging as a therapeutic approach for psychiatric illnesses, with preliminary evidence of safety and therapeutic potential in eating disorders (EDs) [1, 2]. Notably, a phase 1 trial of psilocybin treatment for anorexia nervosa (AN) demonstrated safety and tolerability, and 40% of participants achieved remission from ED psychopathology at 3-months post-treatment [3]. In individuals with body dysmorphic disorder, psilocybin treatment significantly reduced symptoms at 1- and 12-week follow-ups [4]. Several trials are currently underway for AN (NCT04661514, NCT05481736, NCT04052568, NCT04505189, NCT06399263, MRF2014783) and binge eating disorder (NCT05035927), although the field awaits larger randomized controlled trials and mechanistic studies to confirm the therapeutic effects.
The transdiagnostic therapeutic potential of PAT is hypothesized to be linked in part to the alterations in consciousness that occur during the acute psychedelic experience. For example, in AN, 80% of participants felt that the dosing sessions were one of the top five most meaningful experiences of their life and 60% attributed decreases in body image overvaluation to the experience [3]. The therapeutic importance of the psychedelic experience for EDs is corroborated by the broader PAT literature in which the intensity of the acute experience reliably predicts symptom improvement [5–8]. Although the consciousness-altering effects of psychedelics are hypothesized to mediate or moderate treatment outcomes, some researchers argue that current clinical trial measures fail to adequately assess this critical component [9]. Existing PAT research relies heavily on retrospective, pre-defined psychometric scales or open-ended qualitative methods, both of which risk overlooking nuanced, ED–relevant experiential mechanisms.
Phenomenological psychopathology refers to the study of the lived experience of mental disorders and offers a unique opportunity to understand how psychedelics alter consciousness in a manner that may facilitate therapeutic change [10, 11]. Phenomenological psychopathology has been applied to understand clinically meaningful shifts during PAT in treatment-resistant depression, including changes related to the experience of one’s body [12, 13]. However, this approach has yet to be applied in a similar manner to PAT research on EDs and the current trajectory of psychedelic study design suggests that future research efforts may fall short in assessing these outcomes. Therefore, the objective of this scientific commentary is to propose a research agenda that integrates phenomenological concepts with current methodologies to expand the study of experiential therapeutic change markers in PAT for EDs.
The phenomenological study of EDs has contributed to a body of knowledge focused on the subjective, first-person lived experience of EDs and the implications for clinical care [14, 15]. In Table 1, we define and provide a summary of some of the main phenomenological domains associated with EDs, also referred to as the structures of embodiment, intersubjectivity, selfhood, temporality, spatiality and affectivity.
Table 1Summary of phenomenological domains of eating disorders and their definitionsDomainDefinitionRelevance to Eating DisordersEmbodimentThe lived experience of having and being a body, through which the world is perceivedFeelings of estrangement from the body and a disconnect between inner experience and external appearance, contributing to distorted perception of body shape and sizeIntersubjectivityHow we experience others and are shaped by their perceptions, such as how one is seen or judgedHeightened sensitivity to others’ gaze may contribute to body image concerns and efforts to meet societal ideals of appearanceSelfhoodThe sense of being a unified, continuous self with personal identity and self-worthLow self-worth may drive disordered eating behaviours aiming to control identity or mask feelings of inadequacyTemporalityThe subjective experience of time and continuity across past, present, and futureTime may feel distorted or rigidly structured, such as anxiety about time passing or ritualized time (e.g., scheduling eating or exercise)SpatialityThe subjective experience of the body in space and how this perception influences behaviourFear of occupying more physical space may drive disordered behaviours such as starvation or overexercisingAffectivityThe capacity to feel and be emotionally affected by the world, including the salience of experiencesEmotional blunting/dysregulation, difficulty distinguishing emotions from bodily sensations and disordered eating behaviours as a coping mechanism
To further elaborate on the concepts described in Table 1, individuals with EDs may report estrangement from their own body (i.e., disrupted embodiment) [16–18] or changes in how their body is perceived or objectified by others (i.e., altered intersubjectivity), such as adopting a more allocentric (third-person) opposed to egocentric (first-person) perception [19–21]. These alterations may contribute to ED symptomatology, including ED behaviours that attempt to align with perceived ideals of the external gaze [21]. Further, disruptions in selfhood are considered relevant to the onset and persistence of EDs, in which body image concerns may manifest from a deeper dissatisfaction with selfhood and an over-identification with the ED itself [21–23]. From a therapeutic perspective, restoration of a coherent, valued sense of self is increasingly recognized as a feature of recovery [24–26]. Importantly, for some individuals these experiences of embodiment or selfhood may not represent a “restoration” of a previously intact state, but rather the emergence or development of such capacities for the first time.
The phenomenological domains of temporality (i.e., experience in relation to time) [27, 28], spatiality (i.e., the experience of the space one’s body occupies) [21, 29] and affectivity (i.e., the capacity for emotional experience/expression) [30, 31] are also altered in EDs and have been implicated in maladaptive thoughts and behaviours. For example, Stanghellini and Mancini (2019) found that 77.8% of individuals with EDs reported at least one anomalous temporal experience, such as anxiety about time passing or the ritualization of time [27]. Phenomenological inquiry has also contributed to the understanding of distorted spatial experiences in EDs and how fear of occupying too much space is associated with maladaptive coping strategies (e.g., body checking, overexercising and starvation) [21, 29]. Similarly, alterations in affectivity—restrained or dysregulated emotional expression—in EDs has been associated with a reduced capacity to differentiate one’s bodily experience from one’s emotional experience, manifesting as adopting ED behaviours in response to emotions (e.g., emotional over or under-eating) [30].
The subjective psychedelic experience—characterized by acute alterations in perception, self-awareness, affect, and cognition—is regarded as an important moderator/mediator of therapeutic outcomes and purportedly alters several of the phenomenological domains relevant to EDs: embodiment, intersubjectivity, selfhood, spatiality, temporality, and affectivity [7, 8, 32]. Broadly, shared characteristics of psychedelic experiences 1) perceptual changes including intensifying visual features, movement, and more complex hallucinations such as geometric patterns or novel landscapes; 2) changes in self-awareness, a loss of sense of self, or ego-dissolution that includes changes in embodiment; 3) increased feelings of connectedness across several domains, including self, others, nature and the world; 4) altered perceptions of time (e.g., feelings of timelessness or transcending time); 5) a broader and more intense range of emotions; and 6) enhanced perceived insight into several domains of experience (e.g., identity, values, relationships, and illness) [12, 33]. In EDs, qualitative reports vary and different features of psychedelic experiences may be tied to meaningful therapeutic change across participants [3, 34, 35]. Below are some examples of qualitative data gathered from individuals with EDs following PAT:“Ayahuasca helped me deeply connect with myself so that self-love has been the prevalent priority over self criticism that [.] self-love became more important and more prevalent. And that to me is the antidote for an eating disorder.” “I remember having a ceremony where I really saw that at the time binging and purging and restricting were actually adaptive coping mechanisms; at the time, they were the only coping mechanisms that I actually knew to use to deal with the difficulty that I was experiencing, that I had no words for and that no one was asking about.” [36].“I think the first thing that I did was grieve how much I put myself through. I felt like I was forgiving myself for what I’d done and then I had this weird, almost like turnkey thought process of, you don’t have to live as her. And I was able to visualize myself from the outside, like outside of my body and I just saw this version of myself. Almost like a puppet. [.] The way I look, the clothes I wore, the body I was living in, the job I had, the friends I had, the personality I embodied [.] and so I think when I had that moment of, you don’t have to live as her, you could be whoever you want to be without judgment, without anorexia, without all of these things.” [34].
There remains much to be understood regarding which aspects of the psychedelic experience are therapeutic and how best therapeutic experiences can be facilitated and integrated. This gap is problematic as a clear understanding of how altered states interact with pre-existing disruptions in the phenomenological domains of EDs is needed to fully determine how PAT interacts with the psychopathology, and the optimal psychotherapeutic methods to elicit positive outcomes [1, 37]. There are several reasons why existing study designs may not be successful in identifying the clinically meaningful features of psychedelic experiences and, therefore, may benefit from incorporating a phenomenological
First, there is an over-reliance on quantitative psychometric measures which impose pre-existing conceptual frameworks that may not fully align with the lived experience of EDs. For example, in a systematic review of subjective reports in PAT research, 17 different rating scales were employed to assess the psychedelic experience, most commonly the Mystical Experience Questionnaire (MEQ), the Five-Dimensional Altered States of Consciousness (ASC) questionnaire, and the Hallucinogen Rating Scale (HRS) [38]. However, as argued by Miceli McMillan et al. (2024), psychometric measures assess a limited range of pre-defined constructs and risk missing subtle or undefined but potentially meaningful experiential variations [33]. Similarly, current instruments may attempt to quantify phenomenological constructs that remain conceptually elusive, resulting in a loss of granularity [33]. To determine its therapeutic mechanisms, the inherently first-person nature of psychedelic experiences necessitates a qualitative approach that privileges the subjective account and facilitates a deeper understanding of the relevant domains of lived experience [39, 40].
Qualitative interviews are commonly used to document the psychedelic experience in both clinical and healthy populations, employing a participant-directed, inductive approach to data collection and analysis that is largely open-ended and exploratory [41, 42]. While this approach can provide important subject-driven insights about experience, it does not allow for a thorough investigation of the specific phenomenological domains introduced herein. In other terms, existing experiential measures used often focus on quantifying alterations in the content of psychedelic experiences (i.e., what one experiences), rather than the form or structure of the experiences (i.e., how one experiences) [9]. While the content of psychedelic experiences can hold importance via personal significance and symbolic value, characterizing the structural alterations that make this content possible may facilitate a more generalizable understanding of the therapeutic effects of psychedelic experiences. For example, phenomenological psychopathology studies have demonstrated that some psychiatric conditions involve alterations in how one experiences the flow of time (e.g., sense of a foreclosed future, or impending end) while psychedelic experiences may restore such alterations [9, 33]. A more precise theoretical and conceptual framework (i.e., phenomenology) may therefore identify new experiential therapeutic mechanisms of PAT that are relevant to EDs.
Commonly used instruments often fail to address domains of experience that are relevant to EDs, such as the impact of PAT on self-identity which has been associated with enduring behavioural changes in substance use disorders [43, 44]. Alterations in spatiality and temporality are mentioned via psychometric items such as “My sense of time and space was altered as if I was dreaming” (ASC) or “Loss of usual sense of time/space” and “experience of timelessness” (MEQ), although these items may facilitate incomplete or reductive reporting of spatial and temporal experiences [33]. Shifts in pre-existing disturbances in embodiment, intersubjectivity, and affectivity are not a focus of most psychometric measures employed in PAT [45, 46]. Further, there are complex conceptual relationships between ED subtypes and other DSM-5 diagnostic categories, such as shared domains of obsessive thinking and compulsive behaviours with obsessive-compulsive disorder [47–49]. Phenomenological work may be useful in evaluating trans-diagnostic comparisons to produce a clearer conceptualization of diagnostic boundaries [50].
Together, there is a reasonable case to incorporate phenomenological approaches in PAT research on EDs to provide a more focused, empirical view of the experiential effects of PAT on the psychopathology at a level that is not being accomplished in current study designs. Phenomenological measures and concepts have already been used to successfully identify how psychedelic substances alter the structures of experience [51]. A clearer understanding of the psychedelic experience in EDs may help delineate which aspects of PAT are therapeutic versus adverse, and the optimal psychotherapeutic approach to pair with psychedelic administration for positive outcomes in this clinical population.
There are several recommendations that can be made to advance phenomenological approaches to the psychedelic study design in a manner that is both practical and clinically meaningful for EDs. Broadly, we recommend a mixed methods study design that employs one of the following phenomenological methods as appropriate for the research question.
Phenomenologically Grounded Qualitative Research (PGQR) is an approach that can be used to investigate underexplored or ambiguously described aspects of complex experiences, using a focused interview guide to help participants reflect on specific domains such as embodiment, affectivity or selfhood [11, 52–54]. In the study of EDs, PGQR may help the participant explore nuanced bodily experiences that are typically difficult to articulate and that they may have never attended to before. While the researcher defines the initial focus of the study, the data collected is entirely participant-determined. For example, if conducting a study of embodiment in EDs, the researcher would formulate prompts and questions that get the participant to reflect upon and describe their bodily experiences but would not design the questions in such a way that they presume which kinds of bodily experiences the participants have. In some cases, this intensity of reflection is only achieved through several rounds of follow-up interviews, where participants have the opportunity to continue elaborating their experiences across sessions [55]. PGQR is inspired by a similar approach in cognitive science, in which phenomenological concepts are “front-loaded” into the study design to ensure there is a well-defined target for the study [56]. This approach has contributed to a better understanding of the lived experience of diverse conditions, including temporal experiences in social anxiety disorder [57], affective experience in long-term grief [58], and embodied experiences in hemi-spatial neglect [59], among other topics.
Microphenomenology is an interview technique focused on accessing and describing short-lived experiences that occur pre-reflectively (i.e., before conscious reflection or analysis), shifting attention from “what” the participant is experiencing to “how” they are experiencing [60, 61]. For example, instead of being “Did you feel more connected to your body after psilocybin treatment?” participants may instead be “Can you describe, step by step, how the feeling of connection to your body began—what was the first sign, and how did it develop?” Originating from the elicitation interview and mindfulness practices, microphenomenology was developed to bridge subjective experience with objective data, such as in neurophenomenology where neurobiological data is analyzed as a correlate to subjective experience measures [62, 63]. For example, Timmermann et al. (2019) used microphenomenology alongside electroencephalography to demonstrate a negative association between neuronal activity and changes in bodily awareness during dimethyltryptamine (DMT) experiences [64]. Unlike PGQR, which focuses on enduring modes of experience, microphenomenology targets minute, fleeting aspects, such as the experiential precursors to epileptic seizures or momentary rumination in EDs [65, 66]. It is now used, not only in combination with neuroscientific measures but also as a standalone qualitative method and may be complementary to PGQR by offering a finer-grained view of psychedelic experiences.
As most experiential assessments are administered after the dosing session, the development of quantitative rating scales to administer during the acute experience may better capture temporal nuances before these details become obscured and oversimplified retrospectively [67]. As suggested by Yaden et al. (2024), cognitive interviewing may be employed to assess how participants understand the questionnaire items of conventional psychedelic experience measures, contributing to a better understanding of their experiential validity [68]. Similarly, experience sampling involves the repeated collection of real-time data and offers another method to capture psychedelic experiences dynamically throughout dosing and follow-up periods [69]. For example, Holze et al. employed visual analog scales every 30–60 min during lysergic acid diethylamide (LSD) and psilocybin experiences [70, 71].
While PGQR and microphenomenology offer valuable tools to explore the subjective experience of PAT in EDs, it is important to consider the limitations of these approaches [72]. The reliance on pre-defined structures of experience in PGQR may constrain the capture of novel or emergent psychedelic experience and its multi-session format may be impractical in certain contexts. Microphenomenology may pose challenges in attempting to assess the non-linear, ineffable nature of psychedelic experiences and there is little known about the possibility that such detailed recall may be distressing for ED populations. Both methods are relatively cognitively and emotionally demanding on participants and require specialized researcher expertise. As such, each approach should be adapted as appropriate to the unique study design being conducted [41].
This scientific commentary presents the case for phenomenological approaches as a complementary tool to improve our understanding of the experiential correlates of PAT outcomes in EDs. Capturing granular shifts in the relevant structures of experience—embodiment, intersubjectivity, affectivity, temporality, spatiality and selfhood—may contribute to a better understanding of the clinical significance of psychedelic experiences and generate testable hypotheses for future research to advance psychedelic interventions for EDs.