Background: It is known that there is a relationship between psychotic disorders and the presence of cerebral midline defects, such as the cavum septum pellucidum and the absence of adhesio interthalamica. This study aims to investigate whether these defects in people with alcohol/substance use disorders are associated with the occurrence and persistence of psychotic symptoms. Methods: The files of the patients who were hospitalized in an addiction inpatient unit were retrospectively scanned. The presence of cavum septum pellucidum and the absence of adhesio interthalamica were determined by evaluation of the magnetic resonance imaging findings. The presence of psychotic symptoms at admission and the persistence of psychotic symptoms after 2 weeks of detoxification treatment were used as dependent variables in different logistic regression models. The presence of cavum septum pellucidum and the absence of adhesio interthalamica were included in 2 separate models as independent variables. Results: The results of the regression analyses showed no significant relationship with respect to cavum septum pellucidum. However, the analyses revealed that the absence of adhesio interthalamica increases the risk of the persistence of psychotic symptoms. Conclusion: Our findings suggest that the absence of adhesio interthalamica can be considered a structural risk factor for the development of psychosis in people receiving treatment for substance use.