Overall risk of CUD on schizophrenia was slightly higher among men than women.
Young men might be particularly susceptible to the effects of cannabis on schizophrenia, according to a study published online May 4 in Psychological Medicine.
Carsten Hjorthøj, Ph.D., from the University of Copenhagen in Denmark, and colleagues estimated the fraction of schizophrenia cases that could be attributed to cannabis use disorder (CUD) on the population level. The analysis included data from a nationwide Danish register-based cohort of 6.9 million individuals aged 16 to 49 years during 1972 to 2021.
The researchers found that the overall risk of CUD on schizophrenia was slightly higher among men (adjusted hazard ratio, 2.42) than women (adjusted hazard ratio, 2.02). Risk more than doubled for men versus women among those aged 16 to 20 years old (adjusted incident rate ratios, 3.84 and 1.81 for men and women, respectively). The annual average percentage change in the population attributable risk fraction for CUD in schizophrenia incidence over time was 4.8 among men and 3.2 among women. The population attributable risk fraction in 2021 among men was 15 percent compared with 4 percent among women.
“At a population level, assuming causality, one-fifth of cases of schizophrenia among young males might be prevented by averting CUD,” the authors write. “Results highlight the importance of early detection and treatment of CUD and policy decisions regarding cannabis use and access, particularly for 16- to 25-year-olds.”