Cannabis is among the most widely used substances globally. The prevalence of lifetime cannabis use (LCU) is estimated at 27.2% in the European Union.1 Among regular cannabis users, approximately 10% develop cannabis use disorder (CUD),2 defined as a problematic pattern of use resulting in clinically significant impairment.3 Cannabis use has been linked to disorders with psychotic symptoms, including schizophrenia (SCZ), with psychosis as a defining feature, and bipolar disorder (BIP), with an estimated prevalence of psychosis at 73.8%.4 Compared with the general population, persons who reported using cannabis suffer a higher risk and an earlier onset of psychotic disorders (i.e., SCZ and BIP), alongside more severe symptoms and longer hospitalizations.5–8 LCU is less strictly defined than CUD but is linked to adverse outcomes and is genetically associated with other substance use phenotypes and disorders.9 However, the nature of this connection between psychotic disorders and cannabis use has been the topic of much debate within the field of psychiatry and beyond.
