Matthew Johnson is a Professor of Psychiatry and Behavioral Sciences at Johns Hopkins University and a core member of the Johns Hopkins Center for Psychedelic and Consciousness Research. His work focuses on the use of psilocybin to treat substance use disorders — particularly tobacco addiction, where his landmark 2014 and 2017 studies found abstinence rates of 67–80% at 12-month follow-up, far exceeding standard interventions. He has also published extensively on psilocybin dosing science, safety protocols, and the pharmacology of psychedelic experiences.
Johnson joined the Griffiths lab at Hopkins as a postdoctoral fellow in the mid-2000s and became the principal investigator on the landmark tobacco cessation study — one of the most striking results in addiction medicine in recent decades. The study enrolled 15 smokers who had averaged 19 cigarettes per day for 31 years and had failed multiple quit attempts. After two or three psilocybin sessions combined with cognitive behavioral therapy, 80% were abstinent at 6-month follow-up. Twelve-month abstinence rates were 67% — compared to roughly 25% for varenicline (Chantix), the most effective pharmaceutical option.
Johnson's theoretical contribution to the field is his analysis of how psilocybin disrupts addiction. His model proposes that addiction is characterized by hyper-focused, rigid patterns of thought and behavior — essentially an attractor state that the brain returns to compulsively. Psilocybin's disruption of the Default Mode Network and its promotion of neural entropy temporarily expands the accessible cognitive state space, allowing the addicted brain to access perspectives and motivational frameworks that chronic use had made neurologically inaccessible.
He has since extended this framework to alcohol use disorder, opioid use disorder, and cocaine dependence, and has become one of the field's primary voices on safety protocols and risk mitigation. His 2008 safety guidelines for human psychedelic research, published in Psychopharmacology, remain the standard reference for institutional review boards and clinical researchers worldwide.