Adolescent cannabis use may follow the same pattern as alcohol use

A new study published in the journal Addiction shows that cannabis use among Swedish adolescents appears to follow the same population-level pattern previously observed for alcohol. The findings suggest that changes in average cannabis use among young people are reflected across the entire group—from those who use it infrequently to those who use it frequently.

The study is based on extensive data from the Swedish Council for Information on Alcohol and Other Drugs’ (CAN) national school surveys and includes more than 250,000 students aged 15–18 years (in grade 9 and the second year of upper secondary school in Sweden) between 1990 and 2023. The researchers examined how frequently adolescents who already use cannabis do so, and how the distribution of use has changed over time.

A key finding is that the distribution of cannabis use has remained highly stable over time. When average use increases or decreases, the change occurs in parallel across all user groups.

“Increases in average use are not driven solely by a small group of heavy users, but by broader changes in behavior among users in general,” says Thor Norström, co-author and Professor Emeritus at the Swedish Institute for Social Research at Stockholm University.

The study also shows that periods of higher average use coincide with a marked increase in the proportion of adolescents who use cannabis very frequently. In other words, when average use rises, so does the number of young people at risk of cannabis-related problems.

The findings support the so-called total consumption model, a theory that has had a major influence in alcohol research and emphasizes that preventive efforts cannot be limited to high-risk groups alone. Instead, interventions must target the entire population, as changes in norms, availability, and attitudes affect all users simultaneously.

“Our results suggest that adolescent cannabis use is characterized by collective changes, in which social networks, norms, and the broader societal climate play an important role,” says Håkan Leifman, co-author and researcher at the Department of Clinical Neuroscience at Karolinska Institutet.

The researchers stress that the findings are particularly relevant at a time when attitudes toward cannabis have become more permissive internationally. Even in a country like Sweden, where cannabis remains illegal, changing norms may influence adolescent behavior.

“This underscores the importance of a broad public health perspective in preventive efforts targeting cannabis use among young people,” says Norström.