Overview
- An international mega-analysis in Nature Medicine combined 11 resting‑state fMRI datasets from five countries, totaling 267 participants and more than 500 scans across psilocybin, LSD, mescaline, DMT and ayahuasca.
- Across substances, the study found weaker connections within individual brain networks and stronger communication between higher‑order association systems and sensory and motor systems.
- Key subcortical hubs, including the thalamus, caudate, putamen and the cerebellum, showed increased coupling with sensorimotor circuits.
- A uniform preprocessing pipeline with Bayesian hierarchical models estimated effect sizes and uncertainty and helped reconcile conflicting single‑site reports.
- Drug profiles differed, with LSD and psilocybin showing the most consistent changes, DMT showing larger but less certain shifts, ayahuasca showing more idiosyncratic effects and mescaline landing in between, offering a probabilistic blueprint for future research and regulatory review.