Summary: A new study reveals a strong association between adolescent cannabis use and a significantly increased risk of developing psychotic disorders. This risk appears to be age-dependent, with adolescents particularly vulnerable to the effects of cannabis on their developing brains. Although more research is needed, these findings raise concerns about early cannabis use and highlight the importance of prevention strategies.
Highlights:
- Adolescents who use cannabis are 11 times more likely to develop psychotic disorders.
- The association is stronger in adolescence than in early adulthood.
- Most adolescents diagnosed with psychotic disorders have a history of cannabis use.
Source: Institute of Clinical Evaluation Sciences
A new study published in the journal Psychological Medicine estimates that adolescents who use cannabis are at 11 times greater risk of developing a psychotic disorder than adolescents who do not use it.
This finding suggests that the association between cannabis and psychotic disorders may be stronger than indicated by previous research, which relied largely on older data, when cannabis was less potent than it is today. As a reminder, the average THC content of cannabis in Canada increased from approximately 1% in 1980 to 20% in 2018.
Researchers from the University of Toronto, the Center for Addiction and Mental Health (CAMH), and ICES linked recent data from a population-based survey of more than 11,000 youth in Ontario, Canada , to health service utilization records, including hospitalizations and emergency services. visits and outpatient visits.
The study is the first to show an age-dependent association between self-reported cannabis use and subsequent diagnosis of psychotic disorders, adding to a growing body of research on the mental health risks associated with cannabis .
“We found a very strong association between cannabis use and the risk of psychotic disorders in adolescence. Surprisingly, we found no evidence of an association in young adults,” says lead author André McDonald, who conducted the study at ICES as part of his doctorate at the University of Toronto. McDonald is now a postdoctoral researcher at the Peter Boris Center for Addiction Research and the Michael G. DeGroote Center for Medicinal Cannabis Research at McMaster University.
“These findings are consistent with neurodevelopmental theory that adolescents are particularly vulnerable to the effects of cannabis.”
Among adolescents hospitalized or consulted in the emergency room for a psychotic disorder, approximately 5 out of 6 had already reported having used cannabis. McDonald points out that “the vast majority of adolescents who use cannabis will not develop a psychotic disorder, but based on this data, most adolescents diagnosed with a psychotic disorder likely have a history of cannabis use.”
The researchers could not completely rule out reverse causality, as adolescents with psychotic symptoms may have self-medicated with cannabis before receiving a clinical diagnosis. They also couldn’t account for potentially important factors like genetics and history of trauma.
These limitations do not allow us to state with certainty that cannabis use among adolescents causes psychotic disorders. The authors also note that their estimates are only approximate, suggesting that more in-depth studies with larger samples are needed.
Nonetheless, the findings add to concerns about early cannabis use, particularly in the wake of legalization.
“As marketed cannabis products have become more widely available and have higher THC content, the development of prevention strategies targeting adolescents is more important than ever,” says lead author Susan Bondy, a scientist affiliated with ICES and associate professor at the University of Toronto’s Dalla Lana School of Public Health.
McDonald adds: “Young Canadians are among the heaviest cannabis users in the world. If we follow the precautionary principle, the bottom line is that more needs to be done to prevent early use of cannabis.
About this psychosis and current CUD research
Author: Misty Pratt
Source: Institute of Clinical Evaluation Sciences
Contact: Misty Pratt – Institute for Clinical Evaluation Sciences
Picture: Image is credited to Neuroscience News
Original research: Free access.
“Age-dependent association between cannabis use and risk of psychotic disorders” by André McDonald et al. Psychological Medicine
Abstract
Age-dependent association between cannabis use and risk of psychotic disorder
Background
Epidemiological research suggests that cannabis use among youth is associated with psychotic disorders. However, current evidence is largely based on data from the 20th century, when cannabis was significantly less potent than it is today.
Methods
We linked population-based survey data from 2009 to 2012 with records of health services covered by universal health care in Ontario, Canada, through 2018. The cohort included respondents aged 12 to 24 years old at baseline with no prior psychotic disorder (NOT = 11,363). The primary outcome was the number of days preceding the first hospitalization, emergency department visit, or outpatient visit related to a psychotic disorder according to validated diagnostic codes. Due to nonproportional risks, we estimated age-specific hazard ratios during adolescence (12–19 years) and young adulthood (20–33 years). Sensitivity analyzes explored alternative model conditions, including restricting results to hospitalizations and emergency department visits to increase specificity.
Results
Compared to no cannabis use, cannabis use was significantly associated with psychotic disorders during adolescence (aHR = 11.2; 95% CI 4.6 to 27.3), but not during adolescence. young adult course (aHR = 1.3; 95% CI 0.6 to 2.6). When we restricted the results to hospitalizations and emergency department visits only, the strength of the association increased markedly during adolescence (aHR = 26.7; 95% CI 7.7 to 92.8 ) but did not change significantly during young adulthood (aHR = 1.8; 95% CI 0.6 to 92.8). 5.4).
Conclusions
This study provides new evidence of a strong but age-dependent association between cannabis use and risk of psychotic disorder, which is consistent with neurodevelopmental theory that adolescence is a vulnerable time to use cannabis . The strength of the association during adolescence was significantly greater than in previous studies, perhaps reflecting the recent increase in the potency of cannabis.