Mood disorders and psychotic disorders with co-occurring substance use disorders. Studies on prevalence and diagnosis in a Norwegian psychiatric hospital.

Substance use disorders (SUDs) often co-occur with mental disorders. This comorbidity represents clinical challenges for diagnosis and treatment. In the first study we investigated the prevalence of substance use in 65 psychotic patients aged 17-40 years admitted to psychiatric inpatient care. We used the Addiction Severity Index (EuropASI), the Structured Clinical Interview for DSM-IV disorders (SCID-I) and blood and urine toxicology screens. Based on self-report, current and lifetime rates of SUDs in patients were 50% and 70%, respectively. Toxicology screens confirmed patients’ self- report of recent substance use. The high rate of SUDs in psychotic inpatients has implications for the treatment and the organization of psychiatric care for these patients. \nIn the second study, the main focus was the differentiation between independent mental disorders complicated with SUDs and substance-induced mental disorders. The American semi-structured interview, Psychiatric Research Interview for Substance and Mental Disorders (PRISM), was translated into Norwegian and used in a study of 61 psychotic or mood disordered patients aged 18-65 years admitted to the acute psychiatric ward. Patients had screened positive for substance use. We found that 40 % of patients had current substance-induced mood or psychotic disorder. Based on the PRISM interview, current major depressive episodes (MDEs) were substance-induced in 72% of patients with MDE, of which 57% were alcohol-induced. Current psychotic disorders were substance-induced in approximately one third of patients with psychotic disorders. These substance-induced psychotic disorders were mainly induced by illegal substances. Despite the extensive format of the interview, it was possible to use the PRISM systematically in a busy acute psychiatric ward. Patients mainly had positive reactions to the interview. Diagnostic accuracy in comorbidity patients is important for targeted treatment.