Dark loops: contagion effects, consistency and chemosocial matrices in psychedelic-assisted therapy trials

Introduction

The paper situates itself in the recent revival of clinical research into psychedelic-assisted therapy (PAT), noting a rapid increase in trials and a concurrent rise in public hype and social movements around psychedelics. Earlier research has established promising clinical signals for indications such as depression, PTSD, anxiety in terminal illness and substance use disorders, but the authors argue that growing public enthusiasm, media coverage and participant networks risk reshaping the interventions and the conditions under which trial results are produced. Noorani and colleagues set out to formalise how these social dynamics interact with the logic of causal inference used in randomised controlled trials (RCTs). They introduce the anthropological concept of chemosociality—social bonds emerging from shared chemical exposure—and propose the term "dark loops" for feedback structures that form between trials, participants, communities and media, which are largely unmeasured in existing analyses. The paper focuses on PAT trials that combine psychedelic administration (MDMA and classical hallucinogens) with psychotherapy, explains how these phenomena can breach key causal assumptions (especially components of the Standard Unit Treatment Value Assumption, SUTVA), and offers three strategic responses researchers might adopt: chemosocial minimisation, chemosocial description and chemosocial valorisation. The authors exclude most ketamine trials on the basis that many lack an explicit psychotherapy component and therefore differ in protocol from PAT trials.