Study suggests strong link between teen cannabis use, psychotic disorders
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Key takeaways:
- Teens who used cannabis were 11 times more likely to develop a psychotic disorder.
- Researchers found no such association in young adulthood.
Teenagers who use cannabis have a much higher risk for developing a psychotic disorder compared with their nonusing peers, according to research published in Psychological Medicine.
The study was conducted in the context of cannabis legalization in Canada in 2018, and researchers sought to address the limitations of previous research, they said.
“One of the big questions related to cannabis is whether the relationship between cannabis and psychotic disorders is causal,” André McDonald, PhD, MPH, postdoctoral fellow at the Peter Boris Centre for Addictions Research at McMaster University in Ontario, told Healio. “In recent years, cannabis potency has really increased, so we wanted to know whether the strength of association has increased in parallel with that increase.”
McDonald and colleagues linked population-based survey data from 2009 to 2012 with records of health services covered under universal health care in Ontario, Canada, up to 2018. The cohort included 11,363 respondents aged 12 to 24 years at baseline without a prior psychotic disorder diagnosis.
The researchers found that, compared with no cannabis use, cannabis use was significantly associated with psychotic disorders during adolescence (adjusted HR = 11.2; 95% CI, 4.6-27.3), but not during young adulthood (aHR = 1.3; 95% CI, 0.6-2.6). When the researchers restricted outcomes to hospitalizations and ED visits, the strength of the association increased markedly during adolescence (aHR = 26.7; 95% CI, 7.7-92.8) but again did not change meaningfully during young adulthood (aHR = 1.8; 95% CI, 0.6-5.4).
Of the teens who were hospitalized or visited an ED for a psychotic disorder, roughly five in six had previously reported cannabis use, McDonald said.
“We found that teens who were using cannabis were 11 times more likely to develop a psychotic disorder compared to teens who weren't using cannabis,” McDonald said. “When we restricted the outcome to just hospitalizations and ED visits, the strength of association increased. These numbers are much higher than what previous longitudinal studies have reported.”
McDonald added that the lack of an association between cannabis use and the development of psychotic disorders in young adulthood was unexpected.
“We had a really significant association in adolescence, but we didn't find a significant association in young adulthood,” McDonald said. “It sort of makes sense that you would find a strong association in earlier years based on previous literature, but to find no significant association in young adulthood was surprising.”
McDonald said his team is planning other studies on the topic.
“Primary care providers and pediatricians should just be aware that cannabis use, especially during adolescence, carries risk,” McDonald said.“[These providers should] consider talking to young patients about the risks involved with cannabis use, and really try to adopt a preventive approach where you're getting ahead of this instead of reacting to it.”
For more information:
André McDonald, PhD, MPH, can be reached at mcdona36@mcmaster.ca.
References:
McDonald AJ, et al. Psychol Med. 2024;doi:10.1017/S0033291724000990.
New evidence suggests link between teen cannabis use and psychotic disorders may be stronger than previously thought. https://www.eurekalert.org/news-releases/1044795. Published May 22, 2024. Accessed May 29, 2024.
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