A new study has warned young men who show signs of cannabis addiction have an increased risk of developing schizophrenia.
Researchers, including those from the US National Institutes of Health, analyzed health record data spanning years and representing more than six million people in Denmark to estimate the fraction of schizophrenia cases that could be attributed to cannabis use disorder.
Schizophrenia is a serious mental disorder that affects the way a person thinks, feels and behaves, and patients seem to have lost touch with reality, making daily activities impossible in some cases .
People with cannabis use disorder cannot stop using despite the negative consequences in their lives, which also makes daily activities difficult.
The new study, published in Psychological Medicine, strong evidence of a link between cannabis use disorder and schizophrenia among men and women, with a much stronger association among young men.
Scientists estimate that as many as a third of schizophrenia cases among men aged 21-30 could be prevented by avoiding cannabis use disorder.
“The prevalence of substance use disorders and mental illness is a major public health issue, requiring urgent action and support for people who need it,” study co-author Nora Volkow, director of the National Institute on Drug Abuse (NIDA) at the NIH, said.
“As access to strong cannabis products continues to increase, it is imperative that we expand prevention, screening and treatment for people who may have mental illnesses related to cannabis use,” said Dr. Volkow.
In the research, the scientists investigated how the associations between cannabis use disorder and schizophrenia differed by gender and different age groups, and how these differences changed over time.
They sought to estimate the percentage of all schizophrenia cases that could be attributed specifically to cannabis use disorder, across gender and age groups.
The study found that around 15 percent of schizophrenia cases among men aged 16-49 could be avoided in 2021 by preventing cannabis use disorder.
But for young men between the ages of 21-30, the researchers estimated that the percentage of preventable schizophrenia cases related to cannabis use disorder could be as high as 30 percent.
Scientists also warn that there has been a steady increase over the past five decades in the number of new cases of schizophrenia that could be attributed to cannabis use disorder.
This increase, they say, is likely related to the higher potency of cannabis and the increased prevalence of diagnosed cannabis use disorders over time.
“This study adds to our growing understanding that cannabis use is not harmless, and that risks are not fixed at any one time,” said Carsten Hjorthoj, lead author of the study from the University of Copenhagen.
“It is one of the most frequently used psychoactive substances in the world due to increases in the legalization of cannabis over the past few decades, while at the same time reducing public perception of its harm,” said Dr Hjorthoj .
Researchers call for further studies to examine the mechanisms underlying the higher vulnerability of young men to the effects of cannabis on schizophrenia.