Young people with cannabis use disorder have higher rates of psychiatric disorder diagnosis than peers with other substance use disorders, according to a March 5 study published in The American Journal of Psychiatry.
Led by researchers at Baltimore-based Johns Hopkins University, the study analyzed nearly 700,000 U.S. medical records of 691,806 patients and 49,586 patients age 17 and under, according to a March 17 news release from Johns Hopkins Bloomberg School of Public Health. The median age was 16 for patients with cannabis use disorder and 15 for those with other substance use disorders. About 10% of patients were under age 12, and 10.2% reported starting substance use at age 11 or younger.
The researchers found that among patients age 17 and younger, cannabis use disorder was associated with a 52% higher risk of subsequent schizophrenia, a 30% higher risk of recurrent major depression and a 21% higher risk of anxiety disorders, compared to patients with other substance use disorders.
In contrast, adults with cannabis use disorder have lower risks of psychiatric diagnoses. The study found a 19% lower risk of subsequent schizophrenia among adults with cannabis use disorder compared to other substance use disorders (0.34% vs. 0.42%), along with lower risks of psychosis, recurrent major depression and suicide attempts.
The study authors noted one limitation — the database used “relied on International Classification of Diseases ICD-10 coding by other physicians, so the researchers may not know the exact patient history that led to the diagnosis,” according to the release.
The findings suggest cannabis may affect brain development in young people, potentially increasing the likelihood of psychiatric disorder, while differing risk patterns in adults may reflect earlier onset among vulnerable individuals, according to the release.
