Causality between THC and psychotic symptoms has been outlined in several studies and a potential role for THC in the development of Schizophrenia remains to be assessed.

Retrospective study undertaken in a sample of 124 patients assessed in an Emergency Department (ED) due to psychotic symptoms. Medical records were reviewed to obtain clinical and sociodemographic variables.

(1) To analyse the prevalence of THC consumption among psychotic patients in ED; (2) to establish the prevalence of cannabis-induced psychotic disorder; (3) to underpin the socio-demographic and clinical variables associated with cannabis-induced psychosis.

Personal history of cannabis use 31.5% (6.5% as a single drug.) Accumulated time interval of cannabis use prior to the first psychotic episode: 0 – 5years 15% (3.9% developed psychosis during the first year of cannabis use), 5 – 10years 9.2%, more than 10years 20.8%. Cannabis-induced psychotic disorder (F12.5) was diagnosed in 3.3% of the sample. The prevalence of this diagnosis was the same among male and female patients. The highest prevalence of cannabis-induced psychosis was found among 36–50 years old patients (50%). All patients with a diagnosis of Cannabis-induced psychotic disorder had a personal history of THC use and urine tests had been positive for THC in 75% of the cases. Habitat: 75% urban, 25% rural. Marital status: 50% single, 50% married.

Cannabis use is highly prevalent among patients who present with psychotic symptoms in ED and THC is correlated with psychotic episodes. The prevalence of cannabis-induced psychosis has also increased. Further studies comprising larger samples are warranted.