For the past two decades, Krista Lisdahl has been studying the effects of cannabis on young people, and what she’s found is deeply concerning, especially as the mother of a teenage son. “I see the data coming in, and I know that he’s going to come across it,” she says.
As a neuropsychologist at the University of Wisconsin–Milwaukee, she has encountered many young people who have experimented with cannabis, some even using it on a daily basis. With the increasing push for the legalization of recreational cannabis, these encounters have become more common. In her studies, she has found that around one-third of regular cannabis users exhibit signs of cannabis use disorder, meaning they continue to use the drug despite negative effects on their lives. But Lisdahl believes that more conclusive evidence and conversations about the risks of cannabis use are needed, especially for her son.
However, the messaging around drug use is complex. Anti-drug campaigns have decreased, and young people are receiving mixed messages about the risks of cannabis, with some sources even claiming it is harmless or potentially therapeutic. “Young people are very smart, and they see that adults use cannabis,” says Lisdahl. This makes blanket warnings and prohibitions nearly ineffective.
It has been a decade since the legalization of recreational cannabis in Uruguay and in several U.S. states, and researchers are working to understand changing consumption patterns, the drug’s impact on brain development, and its correlation with mental health conditions such as depression, anxiety, and schizophrenia.
The current data doesn’t provide clear answers: young people are not using cannabis in greater numbers than before legalization, but there are indications of more problematic use. Regular use also coincides with higher rates of mental health issues and the risk of addiction, but there could be other explanations for these trends. Experimental studies in humans and animals could help, but they are hindered by the fact that cannabis is still illegal in many places, and it is difficult to track the various products and potencies that people can now easily access.
As a result, some researchers are concerned that society is heading toward a major public health issue. “I am concerned that this could hit us like tobacco hit us,” says Nora Volkow, director of the National Institute on Drug Abuse. She emphasizes that while the risks of cannabis use are small, “it’s like playing roulette.” In hopes of gaining a better understanding of the risks, her agency funded the Adolescent Brain Cognitive Development (ABCD) study, which began in 2015 and recruited over 10,000 children aged 9 and 10.
