Prevalence and patterns of comorbid mental disorders in a male forensic psychiatric sample: A network analysis

Psychiatric comorbidity is highly prevalent among individuals with mental illness and has implications for severity, prognosis, and functioning. These implications are especially salient in forensic settings, where comorbidity is associated with an increased risk of violent offending among individuals with mental illness. This study aimed to examine the prevalence of comorbidity in defendants charged with violent offenses. Building on previous findings, the study sought to replicate and refine earlier comorbidity clusters by applying a network approach. DSM diagnoses of 617 male defendants admitted to the Pieter Baan Centre (PBC), the Dutch forensic psychiatric observation clinic, between 2016 and 2021 were used. Comorbidity patterns could be calculated in 524 cases. A network analysis (n = 516) was performed using regression coefficients to identify distinct clusters of comorbidity. Prevalence rates were highest for substance-use disorders (55.8 %) and schizophrenia-spectrum disorders (33.4 %). Overall, 70.6 % of the sample met criteria for at least one comorbid mental disorder. The network analysis replicated and extended earlier observations by identifying four clusters of comorbidity: (1) substance use and schizophrenia, (2) depressant substance use, (3) internalizing psychopathology, and (4) impulsivity. Each cluster exhibited characteristic patterns. These findings provide a deeper understanding of the distinct clusters of comorbid psychopathologies within forensic samples and highlight specific vulnerabilities. By elucidating these patterns, this study contributes to the expanding body of literature aimed at refining risk assessments and enhancing therapeutic strategies (e.g. cluster-aware treatment planning and risk assessment) for individuals within the forensic population.