Marijuana Use Increases Schizophrenia Risk in Men

2 min read

May 5, 2023 – A new study says as many as 30% of schizophrenia cases among young men could have been prevented if they had avoided marijuana. 

“The entanglement of substance use disorders and mental illnesses is a major public health issue, requiring urgent action and support for people who need it,” said Nora Volkow, MD, director of the National Institute on Drug Abuse, in a statement. “As access to potent cannabis products continues to expand, it is crucial that we also expand prevention, screening, and treatment for people who may experience mental illnesses associated with cannabis use.”

A person with cannabis (marijuana) use disorder is unable to stop using the drug even though it has a negative impact on their life. Schizophrenia is a mental illness characterized by a disconnection from reality and affects how a person thinks, feels, and behaves. Treatments are available for both illnesses. 

This latest study was conducted in Denmark in a partnership between U.S. and Danish researchers. They found that people of both genders had an increased risk of being diagnosed with schizophrenia if they also had a cannabis use disorder (CUD) diagnosis. But being young, male, and having CUD combined for the highest risk.

Researchers concluded that 30% of schizophrenia cases in 2021 among 21- to 30-year-old men and 15% of cases among men ages 16 to 49 could have been prevented if the men did not have clinical marijuana problems. The study was published this week in Psychological Medicine. It included 50 years of Danish public health data for 6.9 million people who ranged in age from 16 to 49 between 1972 and 2021.

Previous research has shown that the psychoactive ingredient in cannabis called tetrahydrocannabinol (THC) may trigger or worsen schizophrenia. Long-term and heavy cannabis use can alter the way the brain works, and it especially impacts the developing brains of teenagers.