Study finds cannabis use disorder diagnoses rose among teens in California after legalization, erasing a 3-year decline
New diagnoses of cannabis use disorder (CUD) among adolescents in Northern California began climbing after recreational cannabis was legalized in California in 2016, reversing a steady decline in the three years prior, according to a new study published in the journal Addiction led by investigators at Kaiser Permanente and the Public Health Institute.
CUD is a complex condition that involves a problematic pattern of cannabis use. Risk of CUD rises sharply with more frequent use and with earlier age of first use. The researchers say their findings call for disorder-level outcomes to be tracked alongside standard measures of use prevalence and frequency when evaluating the public health effects of cannabis legalization.
The new study shows that cannabis laws are tied to changes in young people’s rates of cannabis use disorder,” said senior author Kelly Young-Wolff, PhD, MPH, a research scientist at the Kaiser Permanente Division of Research. “As potency has risen, it’s more important than ever that families understand this is a product that can be addictive and, for some kids, requires real medical care.”
Researchers analyzed 6 years of electronic health record data from 637,000 adolescents receiving care at Kaiser Permanente Northern California. The periods studied were before the 2016 ballot measure passed, between passage and implementation, and after recreational retail sales began, through early 2020. The cohort had an average age of 14 when the study started, and the demographic makeup of the cohort was similar across time periods.
The study found that CUD diagnoses fell about 6% a year before the 2016 vote and rose about 8% a year after, a reversal of the prior trend. Overall, among the 637,461 adolescents studied, 8,804 were newly diagnosed with CUD over the 6 year study period.
The pattern of CUD diagnosis the research team found echoes a companion study on adolescent self-reported cannabis use they published earlier this year in JAMA Network Open. The study found use was falling before California’s legalization, began climbing after the law passed but before retail stores opened and continued rising to a high of 9.5% in early 2020, when the COVID-19 pandemic began. In 2024 adolescent use was at 6.5% — near where it stood just before legalization.
Read more from the Public Health Institute.
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About the Kaiser Permanente Division of Research
The Kaiser Permanente Division of Research conducts, publishes, and disseminates epidemiologic and health services research to improve the health and medical care of Kaiser Permanente members and society at large. KPDOR seeks to understand the determinants of illness and well-being and to improve the quality and cost-effectiveness of health care. Currently, DOR’s 720-plus staff, including 73 research and staff scientists, are working on nearly 630 epidemiological and health services research projects. For more information, visit divisionofresearch.kp.org.
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