'So many relationships in the room': Participant perspectives on the affordances and challenges of co-therapy in psychedelic assisted therapy.

OBJECTIVES: Psychedelic-assisted therapy (PAT) frequently utilises a "cotherapy" model, in which two therapists jointly support participants throughout dosing and psychotherapy sessions. While common in clinical trials, participant experiences of cotherapy remain underexplored. This study explored cotherapy experiences in PAT with psilocybin for Generalised Anxiety Disorder (GAD). DESIGN: Longitudinal qualitative analysis of participants sampled from a large randomised, open-label, phase 2 clinical trial of psilocybin-assisted therapy for GAD, delivered by clinicians with high levels of qualification, training and supervision. METHODS: Qualitative data were collected from n = 18 participants via 29 semi-structured interviews, conducted before and after dosing sessions. Interviews examined experiences of PAT with a cotherapy dyad. Data were analysed thematically, guided by Affordance Theory to consider how cotherapy dynamics shaped therapeutic possibilities. RESULTS: Three major themes were developed: (1) dose day cotherapy: safety, trust and the realities of access; (2) cotherapy influences therapeutic processes; and (3) cotherapy shapes the impact and credibility of therapeutic insights. CONCLUSIONS: Cotherapy in PAT can be both a safety and supportive measure, and a potentiator of therapeutic processes. Insights from this study can guide clinical practice and future research to harness the potential safety and therapeutic benefits afforded by cotherapy while considering feasibility and accessibility.