Recreational Cannabis Use a Negative for Adolescent Mental Health

Cannabis use that doesn't rise to the level of diagnosable substance abuse disorder was nonetheless associated with negative affects on mental health, national data showed.

In the 2015 to 2019 National Surveys on Drug Use and Health, 2.5% of participants ages 12-17 reported repeated past-year cannabis use to a degree that led to clinically significant impairment or distress and met thresholds for a cannabis use disorder (CUD) diagnosis, according to Ryan S. Sultan, MD, of Columbia University in New York City, and coauthors.

But fourfold more -- 10.2% -- reported nondisordered cannabis use (NDCU), meaning use in the month to year prior that didn't rise to the Diagnostic and Statistical Manual of Mental Disorders (Fifth Edition) criteria for an official diagnosis, according to the cross-sectional study published in JAMA Network Open.

In terms of impact, suicidal ideation was 2.08-fold more likely among those with NDCU (adjusted OR 2.08, 95% CI 1.88-2.29) when compared with those who did not use cannabis at all in the prior year. Major depression was also significantly more common with NDCU (aOR 1.86, 95% CI 1.67-2.08), as were difficulty concentrating (aOR 1.81, 95% CI 1.65-2.00) and slower thoughts (aOR 1.76, 95% CI 1.58-1.96).

NDCU was also associated with problems for these teens and tweens, including arrest (aOR 4.15, 95% CI 3.17-5.43), aggression (aOR 2.16, 95% CI 1.79-2.62), fighting (aOR 2.04, 95% CI 1.80-2.31), truancy (aOR 1.90, 95% CI 1.67-2.16), and lower grade point average (aOR 1.80, 95% CI 1.62-2.00).

Sultan told MedPage Today by email that seeing such adverse effects in patients that aren't experiencing a clear substance use disorder is surprising.

"The core purpose of labeling something as a mental health condition is its linkage to adverse impact on a person's life. These findings are suggestive that cannabis use, even at recreational levels, is linked to adverse outcomes in youth," he said. "In the context of an epidemic of depression and suicidality among youth -- this is concerning."

Building on prior studies, these findings support "subdiagnostic cannabis use" as a risk marker for adverse psychosocial events in adolescence, including major depression and suicidality, according to the researchers.

They pointed to a stepwise severity gradient in the odds of psychosocial associations from nonuse to NDCU and CUD. "This severity gradient was also observed in prevalence values for adverse psychosocial events across all degrees of cannabis use. Furthermore, this observation was corroborated by a stepwise cannabis use frequency trend between NDCU and CUD."

For example, suicidal ideation was nearly three times more likely among those with CUD (aOR 2.92, 95% CI 2.43-3.50) when compared with those who did not use cannabis at all, while major depression was more than twice as likely (aOR 2.42, 95% CI 2.02-2.89). Other outcomes followed a similar pattern.

Researchers noted that cannabis use itself could be a symptom of previously existing issues surrounding mental health, but that it might also make preexisting problems worse.

"Cannabis use in adolescence may represent self-treatment to ameliorate mood symptoms and is also associated with developing major depression," they wrote. However, recent studies have suggested that ongoing use worsens mood symptoms. "Given public perspectives on cannabis as a treatment for depressive symptoms, future longitudinal research is necessary to better describe this association."

As of last month, 21 U.S. states and the District of Columbia have legalized marijuana, with many of the remaining states having either decriminalization or medicinal-use-only policies in place.

As the laws and policies change against a backdrop of fairly positive public perceptions of cannabis use but negative associations between mental health and cannabis, Sultan encouraged discussions surrounding cannabis use among clinicians and patients, noting that cannabis use could act as a "marker" for other issues needing intervention.

"Educators, parents, medical providers, and mental health professionals should be vigilant about screening for and treating cannabis use in youth," he said, pointing out that depression, suicidality, truancy, and poor academic performance can all have long-term negative effects on a young person's life trajectory.

A total of 68,263 participants responded to the survey, ranging in age from 12 to 17. Of those respondents, the average age was 14.5 years, and males comprised 50.9% of the study population.

Limitations to this study included self-reported data that did not account for potential psychiatric comorbidities prior to cannabis use. "If anxiety were a common cause of both cannabis use and psychosocial events, it might partially or even fully account for the observed associations between cannabis use and psychosocial events," the researchers noted.

Due to both the cross-sectional and observational nature of this study, direct causality between cannabis use and psychological events could not be determined.

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