Translated from our German original by AI. The German text was researched, written, and edited by the Psychedelia Foundation team and remains the authoritative version.
An international research group led by scientists at the University of Bath concludes that decriminalizing cannabis, or legalizing it under strict regulation, does not necessarily lead to higher use in the population. What appears problematic instead are heavily commercialized, profit-driven cannabis markets of the kind that have emerged in parts of the United States and Canada.
The analysis, published in the journal The Lancet Psychiatry, examined developments in cannabis policy between 2000 and 2025. It found little evidence that decriminalizing possession of small amounts of cannabis, or tightly controlled models of legalization, leads to an increase in use. Commercial markets look different: there, both consumption and the potency of products have risen. At the same time, rates of cannabis dependence have increased.
The researchers also report a link between commercialized markets and a rise in hospital admissions for psychosis. Cases in which psychotic disorders occur together with a cannabis use disorder were particularly affected. For a direct increase in the overall incidence of psychotic illness, however, the authors found no consistent evidence.
Another part of the work looked at medical cannabis. A review of 54 clinical studies produced only limited evidence of therapeutic benefit in mental illness. While cannabinoids were able to ease sleep problems and certain symptoms in autism in some cases, there was no convincing efficacy for anxiety disorders, post-traumatic stress disorder (PTSD) or psychosis. For depression, no relevant studies were available.
The authors therefore stress that in future reforms of cannabis policy the decisive question is less “whether” cannabis is legalized than “how”. In their assessment, models with strict regulation could reduce the negative consequences of criminalization without promoting the health risks of a commercial mass market.
