Comorbidity of psychotic disorder and substance use disorder in a psychiatry inpatient unit: A retrospective study

Objective: Comorbidity of psychotic disorder and substance use disorder is common. Studies demonstrate that this comorbidity constitutes a major mental health problem. The aim of this study is to investigate sociodemographic and clinical differences between illicit drug users and non-users in hospitalised male patients diagnosed with psychotic disorder. Method: This was a retrospective study evaluating files of 237 inpatients treated between January 2013 and December 2016 in Ege University Department of Psychiatry Male Inpatient Unit with diagnosis of Schizophrenia Spectrum and Other Psychotic Disorders according to DSM-5. Results: Of 237 participants, 16% had a lifetime use of an illicit drug. Participants with substance use disorder had a smaller mean age and shorter duration of education than participants without substance use disorder. Of all the participants with a history of substance use, 76.3% had a history of substance use in the first episode of psychosis. The most preferred substance in 72.4% of the participants with substance use during the first psychotic episode and in 68.4% of all the participants with substance use was cannabis. Treatment compliance was worse in the participants with substance use. Discussion: Our findings show that, when psychotic disorder is comorbid with substance use disorder, age of onset of psychotic symptoms decreases, duration of education shortens and treatment compliance deteriorates. These results should be supported by longitudinal studies using quantitative analysis methods.