Patient Experiences of Psilocybin-Assisted Psychotherapy: An Interpretative Phenomenological Analysis

In recent years there has been a resurgence of quantitative research into serotonergic hallucinogens, notably psilocybin, with randomized trials reporting rapid and sustained reductions in anxiety and depression among people with cancer and in treatment-resistant depression, as well as increases in openness and reports of profound spiritual or mystical experiences. Despite these controlled trials and their quantitative outcome measures, the subjective psychological mechanisms by which psilocybin-assisted psychotherapy produces change remain underdeveloped. Prior qualitative work on psychedelic experiences exists but largely concerns recreational use, non‑comparable populations, non-Western ceremonial contexts, or different compounds; rigorous qualitative studies of serotonergic hallucinogens in clinical treatment settings are rare. Belser and colleagues set out to generate hypothesis‑forming, phenomenological data on how participants make sense of their experiences during psilocybin‑assisted psychotherapy. Using an interpretative phenomenological approach, they analysed semistructured interviews with a subsample of patients from an NYU Phase II double‑blind, placebo‑controlled crossover trial for cancer‑related anxiety and distress. The study aimed to characterise the form and content of participants' dosage‑session experiences, the meanings they ascribed to those experiences in context, and how those experiences related to longer‑term change.

This qualitative study sampled 13 adults drawn from a Phase II, double‑blind, randomized, crossover, placebo‑controlled pilot trial conducted at NYU School of Medicine. The parent trial evaluated the safety and efficacy of psilocybin (oral 0.3 mg/kg) administered in the context of adjunctive psychotherapy for psychosocial distress associated with cancer. In the parent protocol each participant received two drug administration sessions separated by seven weeks, with random assignment to sequence (psilocybin first then niacin 250 mg, or niacin first then psilocybin). The overall treatment package included nine psychotherapy sessions (before, between and after the two 8‑hour drug sessions) and follow‑up assessments out to 6 months. Eligible participants for the qualitative substudy were adults aged 18–76 (mean 50 years) with clinically elevated anxiety or related diagnoses linked to cancer; selection for interview was based on the date of final drug administration, and 13 of 14 approached agreed to participate. Five interviews occurred within 1 week of the second psilocybin session and eight were conducted at approximately 1‑year follow‑up. Participation was voluntary, uncompensated, and approved by the institutional review board. One investigator (ABB) conducted all semistructured interviews in person (one by video link), each lasting about 1.5–2 hours; interviews probed experiences before, during and after treatment, including perceptual, emotional and memory domains, and asked participants which session they believed had been the psilocybin session. Audio recordings were transcribed verbatim and deidentified. For analysis the team used Interpretative Phenomenological Analysis (IPA). An interpretative team of four doctoral students and one master’s‑level member employed a consensus process with rotating roles. Two independent reviewers read each transcript and generated descriptive, linguistic and conceptual notes and initial codes; two independent auditors then reviewed coding and provided feedback, leading to refinement of a codebook. An additional reader ensured all five team members were familiar with each transcript. Themes and subthemes were iteratively developed, defined and related to one another, with computer assistance noted but not detailed in the extract.

Thirteen participants were interviewed and multiple recurrent themes emerged; the team applied frequency labels (general: 12–13 cases; typical: 7–11; variant: 2–6). Primary, general themes included relational embeddedness and perceptual phenomena: all 13 participants spontaneously described significant relational insights or transformations during their psilocybin sessions, and all 13 reported closed‑eye visual phenomena of varying complexity. Relational embeddedness and guiding figures. Participants commonly experienced transformed views of loved ones, increased empathy, forgiveness, and improved post‑treatment relationships. Seven participants described encounters with guiding spirits that typically manifested as visions of loved ones providing reassurance or navigation through challenging imagery; male participants were noted as more likely to report such guides. Sharing aspects of the experience with family sometimes strengthened bonds. Emotional range and catharsis. All 13 reported profound emotional experiences during the session. Eleven participants described exalted moments of joy and 11 described profound feelings of love. Many participants also accessed intense sorrow, grief or previously repressed trauma; several reported genuine catharsis (for example, one man wept for the first time about a father‑son rupture). Six participants wept during the interview while recounting their sessions. Transient psychological distress. Seven participants experienced acute, transient reactions (fear, panic, confusion, paranoia) during sessions; no serious medical or psychiatric adverse events attributable to psilocybin were reported, and no pharmacologic rescue or hospitalisation was required. Nine of 13 described loss or dissolution of ordinary self‑boundaries (“ego death” or loss of 'me‑hood'), which for some was frightening but for others formed part of a therapeutic arc. Four participants described a subsequent process of surrender or ‘‘letting go’’ that led to relief and positive affective resolution. Interconnectedness and embodiment. Participants frequently reported transitions from separateness to feelings of universal or interpersonal interconnectedness, and many found this comforting and empowering. Embodied experiences were prominent: six participants described visions of cancer being ejected or accepted into the body, and several used breath, movement or vocalisation as part of processing; some reported transient loss of bodily perception. Wisdom, ineffability and phenomenology. All participants reported gaining transpersonal insights described as ‘‘wisdom lessons’’ about love, interconnectedness, space‑time or alternate realities; however, 10 participants emphasised ineffability and difficulty translating these insights into words. Visual phenomena ranged from simple geometric patterns to richly structured visions and life‑relevant scenarios. Six participants spontaneously reported synesthetic experiences across visual, auditory, gustatory and somatic modalities. Role of music. All 13 participants described the preselected music playlist as central to their experiences; several characterised music as a conduit, guide or co‑author of the session, and four reported blending of self with musical sounds. Lasting impacts and integration. All participants reported post‑treatment benefits related to life priorities, presence and quality of life; many described lasting identity changes (greater confidence, boundary setting, sense of rebirth). Three participants continued to struggle with integration and one required intensive post‑study psychotherapy to process childhood trauma, yet all three said they would repeat the session. Overall, 12 of 13 participants indicated they would repeat a psilocybin session given the opportunity. Frequency notes and safety. The analysis emphasised that intense affective and perceptual phenomena were common but generally transient and occurable within a supportive therapeutic milieu; there were no serious adverse events documented in the extracted text.

Belser and colleagues interpret these findings as indicating a multi‑dimensional topology of experiential processes that may mediate therapeutic change after psilocybin‑assisted psychotherapy. While prior theory has emphasised mystical or peak experiences as a primary mediator, the study suggests that relational, embodied, affective and perceptual factors also play central roles. Participants’ narratives were strongly relational: encounters with loved ones, forgiveness, and improvements in interpersonal functioning were pervasive and may reflect attachment‑ and relational‑based mechanisms worth integrating into future trials. The researchers further highlight embodiment as an understudied domain in psychedelic trials; participants reported somatic transformations, altered interoception and bodily metaphors for healing that are not typically captured by trial outcome measures. Transient psychological distress was common but, within the study’s therapeutic context, largely tolerable and often followed by constructive surrender and integration; thus, acute difficult experiences were framed not simply as adverse events but as potentially necessary components of therapeutic processing. Other interpretations emphasised the organising role of visions and music: closed‑eye visuals often became central organising motifs for meaning‑making, and music functioned as a conduit or guide during sessions. The authors note lasting impacts across life priorities and identity, with some participants reporting concrete behavioural changes (for example, dietary changes and weight loss). The study’s limitations, as acknowledged by the team, include its focus on the dosage session rather than preparatory and integration psychotherapy, variable timing of interviews (five shortly after dosing versus eight around 1‑year follow‑up) which may influence recall and integration, and the omission in this analysis of therapist–patient interaction details and cancer‑specific spiritual themes (the latter to be reported separately). The authors conclude that psilocybin‑assisted psychotherapy was well accepted by participants in this sample and recommend further research to attend to the relational, embodied, affective and perceptual mediators identified here to better articulate psychological mechanisms of action and to optimise therapeutic benefit.