Schizophrenia is a complex and debilitating mental illness affecting millions worldwide. It is characterized by symptoms, including hallucinations, delusions, disorganized thinking, and a reduced ability to function in daily life. While the exact causes of schizophrenia are still not fully understood, researchers have identified several risk factors contributing to its development. One significant risk factor that garnered attention in recent years is the association between cannabis use disorder, or marijuana addiction, and an increased risk of schizophrenia.
As per the National Institutes of Health, researchers at the Mental Health Services in the Capital Region of Denmark and the National Institute on Drug Abuse (NIDA) at the National Institutes of Health have conducted a comprehensive study suggesting that young men with cannabis use disorder are at an elevated risk of developing schizophrenia. The study, published in Psychological Medicine, examined detailed health records spanning five decades and encompassing over 6 million individuals in Denmark. The aim was to estimate the percentage of schizophrenia cases that could be attributed to cannabis use disorder at a population level.
The study found compelling evidence of an association between cannabis use disorder and schizophrenia in both men and women, with an influential association observed among young men. By utilizing statistical models, the researchers estimated that as many as 30% of schizophrenia cases in men aged 21-30 could potentially have been prevented if cannabis use disorder had been averted.
Both cannabis use disorder and schizophrenia are severe mental disorders that can profoundly impact individuals’ lives. Cannabis use disorder is the inability to stop using cannabis despite experiencing negative consequences. Schizophrenia, on the other hand, is characterized by disruptions in thinking, emotions, and behavior, often causing individuals to lose touch with reality and struggle with everyday activities. Nonetheless, effective treatments exist for both disorders.
NIDA Director and study coauthor Nora Volkow, M.D., emphasized addressing the interplay between substance use disorders and mental illnesses as a significant public health concern. With the expanding availability of potent cannabis products, Volkow stressed the importance of expanding prevention, screening, and treatment options for individuals who may experience mental illnesses associated with cannabis use.
Previous studies have indicated higher rates of daily or near-daily cannabis use, cannabis use disorder, and new diagnoses of schizophrenia among men compared to women. Additionally, early and frequent cannabis use has been linked to an increased risk of developing schizophrenia. However, few studies have examined the relationship between cannabis use disorder and schizophrenia across different age and sex groups at a population level.
To fill this research gap, the investigators analyzed data from nationwide health registers in Denmark, including health records from over 6.9 million individuals aged 16-49 between 1972 and 2021. Using these comprehensive longitudinal data, the researchers explored how the association between cannabis use disorder and schizophrenia varied among age and sex groups and how these differences evolved.
While numerous risk factors are associated with schizophrenia, the study focused on estimating the proportion of schizophrenia cases that could be explicitly attributed to cannabis use disorder across sex and age groups on a population level. The findings revealed that in 2021, preventing cannabis use disorder may have avoided 15% of schizophrenia cases in men aged 16-49, in contrast to 4% among women of the same age range. Among young men aged 21-30, the estimated proportion of preventable schizophrenia cases related to cannabis use disorder rose as high as 30%. The authors highlighted cannabis use disorder as a significant modifiable risk factor for schizophrenia at the population level, particularly in young men.
The study also contributes to existing evidence indicating a consistent increase in the proportion of new schizophrenia cases that can be attributed to cannabis use disorder over the past five decades. The authors suggest that this increase is likely linked to the rising potency of cannabis and the growing prevalence of diagnosed cannabis use disorders over time.
Carsten Hjorthøj, Ph.D., lead author of the study and associate professor at the Mental Health Services in the Capital Region of Denmark and the University of Copenhagen, emphasized that the increasing legalization of cannabis and the diminishing perception of its harm have made it one of the most widely used psychoactive substances globally. Hjorthøj noted that this study reinforces the understanding that cannabis use is not without risks, and those risks can change over time.
The authors acknowledged the need for further research to explore potential differences in cannabis potency and frequency of consumption between young men and women. Additionally, understanding the mechanisms underlying the heightened vulnerability of young men to the effects of cannabis on schizophrenia is crucial. The association of cannabis potency with cannabis use disorder and psychosis could inform public health guidelines, policies on cannabis sales and access, as well as efforts to prevent, screen, and treat cannabis use disorder and schizophrenia effectively.
One Response
Was the possibility that individuals prone to schizophrenia may have self-medicated with marijuana? It is well known that schizophrenics are generally heavy smokers of cigarettes because they find the nicotine within calming.