Study: Teen Marijuana Use Linked to 11 Times Higher Psychosis Risk

Customers shop for marijuana products at a cannabis dispensary in Santa Ana, Calif., on Feb. 18, 2021. John Fredricks/The Epoch Times

As the Biden administration moves to reclassify marijuana as a less harmful drug, a new study published Wednesday in the journal Psychological Medicine found teens who use marijuana are at a significantly higher risk of developing a psychotic disorder.

“We found a very strong association between self-reported cannabis use and risk of psychotic disorder in adolescence,” said lead author André McDonald, who conducted the study at the Institute for Clinical Evaluative Sciences at the Centre for Addiction and Mental Health (CAMH) in Canada. The study was part of Mr. McDonald’s doctoral research at the University of Toronto.

“These findings are consistent with neurodevelopmental theory that teens are especially vulnerable to the effects of cannabis,” he said in a CAMH news release about the findings.

The researchers found an 11 times higher risk of developing psychotic disorders, including schizophrenia, among adolescents who used marijuana compared to those who did not use the drug.

When the analysis was limited to emergency department visits and hospitalizations, they found the chance of developing psychotic disorders was 27 times higher in teens who had used marijuana.

Approximately five out of six teens who were hospitalized or visited an emergency department reported previous use of the illicit drug, according to the data.

“The vast majority of teens who use cannabis will not develop a psychotic disorder, but according to these data, most teens who are diagnosed with a psychotic disorder likely have a history of cannabis use,” Mr. McDonald said.

The goal of the study was to estimate the age-related relationship between marijuana use and psychotic disorders in youth based on survey data from over 11,000 young people in Ontario, Canada, from 2009 to 2012.

Respondents with prior treatment for psychotic disorders were excluded from the data for the purpose of this study.

Canada legalized marijuana for recreational use in 2018.

Stronger Link Indicated Over Previous Research

The authors noted that the findings suggest a stronger link between adolescent marijuana use and psychotic disorders than was indicated in previous research.

“This study provides new evidence of a strong but age-dependent association between cannabis use and risk of psychotic disorder, consistent with the neurodevelopmental theory that adolescence is a vulnerable time to use cannabis,” the study says.

Researchers suggest that the increased potency of marijuana could be a contributing factor, pointing out that past research relied on older data when the level of THC (tetrahydrocannabinol), the primary psychoactive component in cannabis, was much lower.

“The strength of association during adolescence was notably greater than in previous studies, possibly reflecting the recent rise in cannabis potency,” wrote the authors, adding that the “average THC potency increased from less than 1% prior to 1980 to 6% in the late 1990s, 15% in 2016, and 20% in 2018. ... New types of cannabis products have also become more popular, including cannabis extracts, which can reach upwards of 95% THC.”

Why This Study Matters

The authors said the relationship between marijuana use and psychotic disorders in young people is a critical public health issue, especially as more jurisdictions move to legalize the drug and the perception of harm declines.

In the United States, the Department of Health and Human Services (HHS) has recommended that the Drug Enforcement Administration (DEA) reclassify marijuana as a Schedule III drug, downgrading it from Schedule I.

Schedule I drugs, such as heroin and cocaine, are considered to be those with no safe use and a high potential for abuse. Schedule III drugs are defined as drugs with moderate to low potential for abuse and include Tylenol with codeine, ketamine, and anabolic steroids.

Last year, the HHS deemed marijuana less risky to public health than cocaine, heroin, and oxycodone and effective in treating anorexia, pain, and other ailments.

“Although abuse of marijuana produces clear evidence of a risk to public health, that risk is relatively lower than” that posed by other drugs, the agency concluded.

The debate over the risks associated with marijuana continues even as 38 states have legalized the drug for medical use and 24 have legalized it for recreational use.

“The argument that marijuana is as dangerous as fentanyl, cocaine, and meth is laughable,” said Matthew C. Zorn, a Houston-based attorney who writes a newsletter on cannabis regulation. “The DEA isn’t where most Americans are. They’re standing on the wrong side of history.”

But even HHS‘ National Institute on Drug Abuse has issued conflicting statements with HHS’ recommendation to reclassify cannabis, saying the potency of marijuana has been steadily increasing over the years, resulting in higher numbers of emergency room visits to treat a wide range of physical and mental effects, from breathing problems and mental impairment to hallucinations and paranoia.

“Whether smoking or otherwise consuming marijuana has therapeutic benefits that outweigh its health risks is still an open question that science has not resolved,” Nora Volkow, a neuroscientist who leads NIDA, is currently quoted as saying on the institute’s website. A spokesperson at NIDA said rescheduling would facilitate research more into the drug.

NIDA’s most recent medical evaluation of marijuana was in 2015, a year before the Obama administration’s DEA rejected a similar request to reschedule the drug.

This time, after President Biden ordered a review of the drug’s status in 2022, HHS adopted new criteria to reach its rescheduling conclusion, taking into account the states that have already legalized medical marijuana.

The Associated Press contributed to this report.