A study conducted in Basel, Switzerland, as part of the Weed Care project, reveals that legal access to cannabis can lower problematic consumption, particularly among individuals who also use other drugs. The findings, published in the journal Addiction, assess the effects of legal versus illegal cannabis procurement on user behavior and mental health.
The Weed Care study, which launched in January 2023, aims to provide scientific evidence for discussions surrounding cannabis legalization in Switzerland and other countries. Advocates hope that legalization will curb the black market, improve consumer access to safer products, and facilitate counseling, while opponents fear it may normalize use and lead to increased addiction and mental health issues.
In this randomized controlled trial, researchers studied approximately 370 participants divided into two groups. One group was allowed to purchase legal cannabis from nine participating pharmacies and received counseling, while the other group continued to obtain cannabis from the black market. Participants filled out questionnaires regularly to report their consumption patterns and mental health status.
Dr. Lavinia Baltes-Flueckiger, the lead author and deputy head of the study, noted that this is the first controlled, randomized study of its kind. Previous research relied solely on observational data. The results indicated a slight decrease in problematic consumption among those who accessed legal cannabis. Problematic use is defined as consumption that leads to health, social, or psychological difficulties, even without a formal dependency.
More notably, individuals in the legal access group who also used other drugs showed a significant reduction in problematic cannabis use. The study also dispelled concerns that legalization would worsen mental health symptoms associated with cannabis use. After the initial six-month period, no differences in depression, anxiety, or other mental health symptoms were observed between the two groups.
After six months, participants from the control group were granted legal access to cannabis through the pharmacies, as promised at the study’s outset. Following this transition, the interim assessment showed improved mental health among roughly 300 participants still involved in the study.
Professor Marc Walter, head of the study, emphasized that legal access alleviates burdens on consumers. The ongoing research aims to further evaluate the long-term impacts of cannabis legalization on health and consumption patterns. The findings contribute valuable data to the ongoing discussions about cannabis policy in Switzerland and beyond.
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