Patterns of onset and progression of psychoses induced by psychoactive substance use

Drug use in Europe has increased in recent years, including a marked rise in new psychoactive substances (NPS). Substance use disorders negatively affect physical and mental health. Psychotic disorders are highly prevalent among drug users. Establishing a link between illicit drug use and schizophrenia would help clarify the progression risk after substance-induced psychosis.

To investigate the onset and evolution of substance-induced psychosis in patients hospitalized in Brașov Clinical Hospital of Psychiatry and Neurology.

A retrospective observational study, analyzing data from all the patients admitted to the hospital between 2014 and 2024, who were diagnosed with substance-induced psychosis other than alcohol, according to DSM-5 criteria.

Of all admissions, 2353 (9.6%) were diagnosed with acute psychotic disorders, of which 129 (5.5%) were related to psychoactive substances. THC (cannabis) was the main substance used, being present in 82.95% of cases. Almost half of the patients (44.96%) reported multiple drug use. 48.84% of patients required subsequent psychiatric readmissions after a first episode of substance-induced psychosis. 11.62% of the patients with substance-induced psychosis were subsequently diagnosed with a major psychiatric disorder, schizophrenia (N = 10, 7.8%) or bipolar disorder (N = 5, 3.9%). The mean duration of conversion to a major psychiatric disorder was 3.37±3.38 years.

Substance-induced psychosis carried a meaningful risk of later transition to schizophrenia-spectrum or bipolar disorders, particularly among patients with higher-risk substance patterns and other vulnerability factors. THC was the most frequently used substance and emerged as an important risk marker in this cohort, supporting the need for timely recognition, sustained follow-up, and integrated intervention for high-risk patients.