A new study conducted by the Mental Health Services in the Capital Region of Denmark and the National Institute on Drug Abuse (NIDA) found a strong association between cannabis use disorder and schizophrenia, particularly among young men aged 21-30. By analyzing detailed health records data of over 6 million people in Denmark spanning five decades, the researchers estimated that up to 30% of schizophrenia cases among young men in this age group might have been prevented if cannabis use disorder was averted. The study highlights the need for proactive screening, prevention, and treatment of cannabis use disorder among young people.
Cannabis use disorder is a mental disorder characterized by an individual’s inability to stop using cannabis despite negative consequences in their lives. On the other hand, schizophrenia is a serious mental illness that affects a person’s thinking, feeling, and behavior. People with schizophrenia often appear to have lost touch with reality, and their symptoms make it difficult for them to participate in regular everyday activities. While effective treatments are available for both mental disorders, it is essential to expand prevention, screening, and treatment for mental illnesses associated with cannabis use, especially as the legalization of cannabis and decreasing perception of harm make its consumption more prevalent.
Previous studies indicate that the risk of daily or near-daily cannabis use, cannabis use disorder, and new schizophrenia diagnoses is higher among men than women, and early, frequent cannabis use poses an increased risk of developing schizophrenia. However, few studies have examined the relationship between cannabis use disorder and schizophrenia across different sex and age groups at the population level. Through nationwide health records in Denmark, including over 6.9 million people who were aged 16-49 between 1972 and 2021, the study found strong evidence of an association between cannabis use disorder and schizophrenia among men and women, with a much stronger association among young men.
The study estimated that 15% of schizophrenia cases among men aged 16-49 and 4% among women aged 16-49 in 2021 may have been avoided by preventing cannabis use disorder. For young men aged 21-30, the proportion of preventable cases of schizophrenia related to cannabis use disorder may be as high as 30%. The study authors stress that cannabis use disorder appears to be a major modifiable risk factor for schizophrenia at the population level, particularly among young men.
The study’s lead author, Carsten Hjorthøj, warns that while cannabis legalization has made it one of the most commonly used psychoactive substances globally, it is not harmless, and risks are not fixed at one point in time. The authors note that the study’s findings suggest that cannabis use disorder is a crucial modifiable risk factor for schizophrenia, especially among young men. The rise in cannabis potency and the prevalence of diagnosed cannabis use disorder over time may account for the increase in new schizophrenia cases attributed to cannabis use disorder over the past five decades.
Further research is needed to examine potential differences in the potency and frequency of cannabis consumption between young men and women and assess the mechanisms underlying the higher vulnerability of young men to the effects of cannabis on schizophrenia. The study’s findings can help inform public health guidelines, policies on cannabis sales and access, and efforts to prevent, screen for, and treat cannabis use disorder and schizophrenia, researchers argue.
In conclusion, young men with cannabis use disorder are at a heightened risk of developing schizophrenia, according to the study by the Mental Health Services in the Capital Region of Denmark and NIDA. The study’s findings suggest that cannabis use disorder is a critical modifiable risk factor for schizophrenia, particularly among young men aged 21-30. As cannabis legalization expands and the perception of harm decreases, it is essential to expand prevention, screening, and treatment for the mental illnesses associated with cannabis use. Studies such as this one can help inform decisions healthcare providers may make in caring for patients and those individuals may make about their cannabis use.
