Substance use disorder in individuals with schizophrenia

Abstract

Introduction. Schizophrenia can be defined as a mental disorder that affects a person’s thoughts, actions, expression of the emotions, perception of reality, and relations with other people. Schizophrenia is one of the top 15 leading causes of disability. The World Health Organization (WHO) reports that worldwide, one out of every 300 individuals is affected by this disorder, and its prevalence on a global scale varies between 0.3-0.7%. The critical age of onset and behavioral manifestation for schizophrenia occurs at the end of adolescence or early adulthood, and it is notably lower in substance users compared to patients without any form of abuse. Drug consumption among patients with schizophrenia varies, but cannabis, alcohol and cocaine remain among the most commonly used substances, significantly impacting symptoms and disease management. Aim of study. Schizophrenia and substance abuse commonly share overlapping risk factors, including genetic predisposition, environmental influences, and neurobiological vulnerability, contributing to their heightened co-occurrence. Their association is correlated with a higher frequency of relapses, extensive manifestations of positive symptoms, depression, cognitive impairments, less favorable outcomes, and ineffective responses to treatment. It is also notable that the age of onset for schizophrenia is significantly lower in drug users compared to patients without a history of abuse. The remarkable association between schizophrenia and substance abuse, especially among patients experiencing their first episode of the illness, is a significant and intriguing aspect in mental health research. Employing dual therapy, which integrates interventions addressing both mental health and substance dependency, is frequently crucial for ensuring a holistic and efficacious approach. Methods and materials. An advanced search was performed in the PubMed and Medline databases, taking into account relevant articles, published in the last 10 years. We used the following keywords and word combinations to search for: ”Substance abuse”, ”schizophrenia”, ”Substance use disorders”. Results. According to existing data in the specialized literature, the prevalence of substance use disorders (SUD) in individuals with schizophrenia is estimated to be between 20% and 65%, with variations across different studies. Patients with schizophrenia have a significantly higher risk of experiencing SUD compared to the general population. The relationship between SUD and schizophrenia is explained by four hypotheses, including the self-medication hypothesis, common vulnerability hypothesis, the theory of dysregulated dopaminergic reward system and the hypothesis of treatment side effects. However, the exact directionality of the relationship between substance use and schizophrenia remains unclear. Multiple studies suggest a high prevalence, approximately 35%, of substance abuse in the first episode of schizophrenia. The most commonly abused substances in schizophrenic patients were cannabis, followed by alcohol. Scientific research appears to indicate that a younger age of onset in the abuser group, male gender, lower education level, and the use of psychostimulants are factors associated with the onset of schizophrenia at an early stage of life, leading to a higher risk of dependence, increased severity of psychotic symptoms, and ultimately, a variety of poorer outcomes. Conclusion. In conclusion, the intricate relationship between schizophrenia and substance abuse, particularly in the context of the first episode, underscores the need for a comprehensive understanding and integrated therapeutic approaches.