Synergies in psychedelic-assisted therapy: a qualitative interview study of psychotherapeutic processes

Interest in psychedelic-assisted therapy (PAT) has increased sharply over the past decade, with previous studies suggesting benefits for conditions such as depression, post-traumatic stress disorder, addiction, anxiety, and end-of-life distress. At the same time, there is an unresolved debate about how much of PAT’s effect comes from the psychedelic substance itself and how much comes from the psychotherapeutic context in which it is delivered. The paper situates this discussion within the idea that psychedelics are highly context-dependent and that “set and setting”, preparation, and post-session integration may be central to outcomes. It also notes that current research often gives limited attention to the therapeutic framework, even though patients in clinical and some research settings commonly receive psychological support from trained therapists. Stellmacher and colleagues therefore set out to explore how psychotherapy contributes to PAT in Switzerland, where psychedelic treatments can be delivered in long-term clinical frameworks outside formal trials. Rather than asking whether psychotherapy matters, the study asks how and why psychotherapeutic processes shape PAT, and how they interact with the psychedelic experience. The authors framed the inquiry around three possible relationships between psychedelics and psychotherapy: a mainly psychopharmacological view, a catalyst view in which psychedelics amplify psychotherapeutic processes, and the possibility that PAT constitutes a distinct class of psychotherapeutic process. The study was designed as a qualitative interview study of Swiss therapists practising PAT. This focus is particularly relevant because Swiss clinical practice allows psychedelic sessions to be integrated over extended periods into ongoing psychotherapy, offering a setting that differs from the shorter, more standardised support structures often used in trials.

The study used a qualitative design based on semi-structured interviews with Swiss therapists who were practising PAT under special licences from the Federal Office of Public Health outside research settings. The researchers focused on therapists with psychiatric or psychotherapeutic qualifications because the paper was concerned with how psychotherapy itself is enacted within PAT. The inclusion criteria were that participants had a psychotherapeutic background as either a psychiatrist or psychological psychotherapist, had treated at least three patients with psychedelics, and had conducted at least ten psychedelic dosing sessions. Seven therapists took part; four were men and three were women. Participants were recruited through the study team’s professional network. Interviews were conducted either in person or via Zoom, at times and places convenient for the participants. All interviews were audio-recorded and transcribed, with a mean duration of 76 minutes. The study had ethics approval from the Universitätsmedizin Greifswald Ethics Committee and was preregistered on OSF.io. The interviews were carried out in German. The semi-structured interview guide covered three broad areas: participant background, the therapists’ approach to PAT, and their views on the interaction between psychedelics and psychotherapy. In the final section, participants were also shown a triangle diagram representing three perspectives on the psychedelic-psychotherapy relationship and asked to indicate where they positioned themselves. Quotes used in the paper were translated into English and checked against the original meaning. The data were analysed using thematic analysis combining inductive and deductive coding. Most codes were generated inductively, while some were informed by the three pre-specified perspectives. The first author completed the main analysis in MAXQDA 24, moving iteratively through familiarisation, coding, theme development, review, and refinement. To improve rigour, participants were shown paraphrased transcript segments for clarification, and coding was additionally reviewed by a PAT researcher and another researcher unfamiliar with PAT; any differences were discussed to reach agreement.

The analysis produced two main themes: “Psychotherapy as the Foundation of PAT” and “A Synergistic Relationship”. Together, these themes described both the concrete psychotherapeutic practices used in PAT and the deeper interaction between psychedelics and psychotherapy that therapists said emerged in clinical work. Under the first theme, therapists described PAT as unfolding across preparation, dosing, and integration phases. In preparation, they aimed to build rapport, provide psychoeducation, and help patients adopt a curious, accepting attitude rather than resist the experience. This included encouraging patients to “drift” with the experience, reduce control and avoidance, and manage expectations so PAT would not be seen as a “magic pill”. Therapists also emphasised mindfulness training before dosing sessions so that patients could remain calm, notice emotions and bodily sensations, and engage with music or other stimuli more openly. During dosing sessions, therapists focused on creating a safe, welcoming environment with mattresses, blankets, pillows, music, drinks, and easy access to a quiet space or restroom. They saw the room and their own demeanour as part of the therapeutic setting. Most of the time they adopted a non-directive, attentive stance and avoided unnecessary intervention. When support was needed, they used what they described as “gentle impulses”: cautious, intuitively timed interventions that were often sensory-based rather than heavily verbal. These might involve touch, sound, music, smell, or brief validating comments, especially when a patient was distressed, overwhelmed, or at risk of impulsive behaviour. In integration, therapists stressed the importance of helping patients verbalise what had happened during the dosing session, sometimes while the acute effects were fading, and then exploring meaning in later psychotherapy. They saw this as a way of making implicit emotions, memories, and relational patterns more conscious and potentially usable for change. Integration was considered especially important when patients had difficult or incomplete experiences, or when transferential dynamics emerged during the session. The second theme described a synergistic relationship in which psychedelics intensify core psychotherapeutic processes. Therapists frequently said psychedelics act as “catalysts”. They reported exceptional profundity in sessions, including stronger emotional intensity, reduced defences, and a deeper embodied understanding of issues that had previously been understood only intellectually. They also described trust as central throughout PAT. Trust had to be built during preparation, but could be deepened by the shared intensity of dosing sessions. Some participants felt that this trust made it easier for patients to enter the psychedelic experience and for therapists to stay responsive during it. Therapists reported that patients could have a wide range of experiences, including empathy, insight, recognition of strengths, fuller acknowledgement of past suffering, bliss, unity, or spiritual depth, but also anxiety, trauma-related material, and other challenging emotions. They viewed these experiences as potentially therapeutically useful when properly supported and integrated. When asked to compare the three perspectives, participants most often favoured the view that psychedelics catalyse psychotherapeutic processes. The purely psychopharmacological view was also acknowledged in some cases, and the idea of PAT as a wholly distinct psychotherapeutic class was mentioned least often and with scepticism. On the triangle diagram, all participants marked positions close to the catalyst perspective, although some also allowed for the other two views in particular situations.

The authors interpret the findings as evidence that PAT in the Swiss clinical context is strongly shaped by psychotherapy and by the interaction between psychotherapy and psychedelics rather than by the drug alone. They argue that preparation, the dosing environment, therapist presence, and integration work are all active elements of treatment, not just safety measures. In their view, trust, emotional depth, and meaning-making are central processes that can be amplified by psychedelics and then carried into ongoing psychotherapy. They also suggest that the therapists’ emphasis on psychedelics as catalysts fits with earlier psychedelic research and with psycholytic therapy traditions from the 1950s. The paper positions these findings against the ongoing debate about whether PAT effects should be attributed mainly to pharmacology or to psychotherapeutic context. The authors note that while some research and regulatory discussions emphasise minimal supervision and pharmacological action, their participants described a more integrated clinical model in which psychotherapy is essential. They also point out that the Swiss context differs from many trial settings because PAT can be embedded in long-term treatment, allowing repeated preparation, dosing, and integration over time. They suggest that this may help explain why therapists in this study gave such strong weight to psychotherapeutic factors. The authors acknowledge several limitations. The sample was small, with only seven therapists, all from similar professional backgrounds and some professionally connected, which may have encouraged shared views. The study did not include non-psychotherapeutic perspectives, so it may have overemphasised the importance of psychotherapy relative to other psychedelic contexts. The authors also note that participants were all primarily psychotherapists, even when they had medical training. They recognise the broader difficulty of placebo control and blinding in psychedelic research and caution that the findings are not directly transferable to all PAT models or all regulatory settings. For future research, the authors call for comparisons across PAT models with different levels of psychological support, including more passive supervision and more directive therapist involvement. They also recommend observational studies in routine clinical practice and further work on common psychotherapy factors such as trust, emotional depth, and meaning. They suggest that more attention should be paid to the ethical and practical use of touch and to the nature of the deep therapist-patient bond that can develop in PAT.

The authors conclude that psychedelic effects are context-dependent and that psychotherapy can meaningfully shape both the experience and the outcomes of PAT. They argue that the current Swiss clinical model appears to increase the likelihood of therapeutic experiences by embedding psychedelics within a professional psychotherapeutic framework. In their view, a strong therapeutic relationship, a safe environment, and immediate psychological support are not only important for safety but may also help optimise therapeutic effects. They present the study as a qualitative contribution to understanding how psychotherapy may exert its influence within PAT and argue that these psychotherapeutic dimensions deserve further investigation.