Co-Morbid Substance Use in Psychotic Disorder: The Role of a Neurocognitive Dysfunction

Background and aims: Psychotic disorders (PD) are often accompanied by substance (ab)use. Recent studies demonstrated a connection between these conditions through a common neurocognitive dysfunction. This common dysfunction concerns the executive functions (EF). Through this way it affects both cognitive control and mechanisms of motivation/reward. An EF dysfunction is a core feature of both PD and substance (ab)use. Moreover, it is found to be present prior to the onset of both conditions. It is suggested that this common EF dysfunction highlights a vulnerability for comorbidity. Hence, this study investigated whether a common neurocognitive dysfunction is associated to the co-morbidity of substance (ab)use and PD. Investigating EF in co-morbidity is especially relevant for theories of aetiology, prevention and treatment. First, we examined whether poor EF predicts an increase in substance use in PD patients. Second, we examined whether poor EF, combined with substance use,...Show moreBackground and aims: Psychotic disorders (PD) are often accompanied by substance (ab)use. Recent studies demonstrated a connection between these conditions through a common neurocognitive dysfunction. This common dysfunction concerns the executive functions (EF). Through this way it affects both cognitive control and mechanisms of motivation/reward. An EF dysfunction is a core feature of both PD and substance (ab)use. Moreover, it is found to be present prior to the onset of both conditions. It is suggested that this common EF dysfunction highlights a vulnerability for comorbidity. Hence, this study investigated whether a common neurocognitive dysfunction is associated to the co-morbidity of substance (ab)use and PD. Investigating EF in co-morbidity is especially relevant for theories of aetiology, prevention and treatment. First, we examined whether poor EF predicts an increase in substance use in PD patients. Second, we examined whether poor EF, combined with substance use, predicts an increase in substance dependency. Methods: This crosssectional study included 90 patients diagnosed with PD (18-65 years). Data were obtained through self-report questionnaires that measured EF, substance use and -dependency. Three multiple linear regression analyses were calculated to evaluate whether EF scores predicted substance use; three moderated binary logistic regression analyses were calculated to evaluate whether EF scores, moderated by substance use, predicted substance dependency. Findings: Results showed that Initiative deficits predicted substance use (p=.01). Deficits of Emotional regulation (p=.04) and Working memory (p=.03), moderated by substance use, predicted a decrease of dependency. Conclusions: Our results partially confirmed that poor EF predicted substance use and -dependency in PD. It did not lend sufficient support for the idea that the co-morbidity of substance (ab)use and PD is associated with a common EF dysfunction. Nevertheless, results demonstrated a relation between EF and substance (ab)use, namely that PD patients use substances as a means of self-medication in order to cope with an EF dysfunction. It can be concluded that this self-medicative behaviour promotes the development of co-morbid substance (ab)use in PD. This study offers new insights into the selfmedication hypothesis. It demonstrated that, besides psychotic symptoms, an EF dysfunction induces self-medicative substance use in PD. Clinical implications may concern prevention techniques and treatment methods.Show less

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Co-Morbid Substance Use in Psychotic Disorder: The Role of a Neurocognitive Dysfunction