The role of substance use disorder in the commission of criminal offenses by subjects suffering from schizophrenia

Introduction. - Although the association between schizophrenia and violence has been established, the mediating role of associated substance use disorder is still debated. Addictive comorbidities, identified in almost half of people with schizophrenia, are considered to be a main explanation for delinquency in this population, regardless of the mental disorder. However, some authors describe the existence of sub-groups of subjects with schizophrenia who may be violent and for whom substance-related disorders would not always be necessary for the emergence of violent behaviors. Objective. - The purpose of this study was to assess the frequency of substance use disorders in subjects with schizophrenia who had committed criminal offenses and to compare the socio-demographic, historical, clinical, and criminal characteristics of these subjects with and without an associated substance use disorder. Method. - We conducted a descriptive study based on forensic reports realized between 2001 and 2018 from a single expert in criminal cases. All reports involving patients suffering from schizophrenia were retrospectively included in our study. Results. - Our sample consisted of 104 subjects suffering from schizophrenia and having committed criminal offenses. A psychoactive substance use disorder (USPA) was found in 52 subjects (50%). There were no significant differences between the two groups in the pattern of infractions committed. However, there were clinical specificities in each group. Thus, offenders with schizophrenia who were non-users of psychoactive substances (NUSPA) had significantly more criminal history of violence against others (73.9% vs. 42.3%; p = 0.026) and more acute psychotic symptoms at the time of the offense (67.3% vs. 30.8%, p < 0.001). The expert more often retained an abolition of discernment in the NUSPA group (68.6 VS 32.7; p < 0.01) and a diminished discernment in schizophrenic subjects using psychoactive substances (USPA) (31.4% VS 67.3%; p <0.01). Conclusions. - Half of the schizophrenic offenders did not have a comorbid substance use disorder. The increased risk of delinquency in subjects with schizophrenia cannot only be attributed to the effects of associated substance use. There is delinquency associated with schizophrenic illness, apart from substance use, that has some specific characteristics that warrant the pursuit of further studies. (C) 2020 Elsevier Masson SAS. All rights reserved.