Psychedelics and the quantum brain: a falsifiable hypothesis on Posner molecules and spin-dependent pharmacology.
Frontiers in pharmacology January 1, 2026 Joseph Geraci, Erik Viirre, Bessi Qorri et al.
Classic psychedelics like LSD, psilocybin, and DMT affect perception and brain plasticity mainly by activating the 5-HT2A receptor and triggering calcium-dependent signaling. A speculative but testable hypothesis suggests these biochemical cascades might connect with quantum processes in the brain, specifically through nuclear spin dynamics in phosphate-based 'Posner molecules' (Ca9(PO4)6). Intense 5-HT2A-driven neural activity and calcium flux during psychedelic use could allow phosphorus nuclear spins in these molecules to become entangled and shielded from decoherence, later influencing neuronal signaling when the clusters release calcium. This framework, building on Fisher's quantum cognition model, proposes testable predictions and outlines short-, medium-, and long-term experiments to confirm or refute quantum involvement, which could transform understanding of mind-brain relationships and psychiatric treatment.