Gray Matter Alterations and Symptom Severity in Forensic Psychiatric Patients: An Exploratory VBM Study

Aim: The relationship between mental illness and criminal behavior is a critical social issue that remains under debate. This study aimed to investigate differences in cortical gray matter (GM) volume between mentally ill individuals institutionalized in a residence for the execution of security measures (REMS) following a violent offense-and deemed not criminally responsible due to their psychiatric condition-and a control group of healthy non-offenders, using voxel-based morphometry (VBM) analyses. Method: We recruited 13 male violent offenders with psychotic disorders institutionalized in REMS and 13 healthy controls. Psychiatric symptoms were assessed using the Brief Psychiatric Rating Scale (BPRS), and psychopathy traits with the Psychopathy Checklist-Revised (PCL-R). High-resolution structural Magnetic Resonance scans were acquired on a 3T scanner. VBM analyses were used to identify GM volume differences between groups, and correlation analyses were performed to assess associations between brain structure and clinical measures. Results: The experimental group showed wide variability in symptom severity and psychopathy traits. VBM analyses revealed GM volume reductions in bilateral insular cortex, in left superior temporal gyrus (STG) and right fusiform gyrus (FG) of the experimental group. GM volume in the left STG-insula cluster significantly correlated with BPRS scores. No significant associations were found with PCL-R scores. Conclusion: These findings highlight structural brain alterations associated with psychotic symptomatology and should serve as a starting point for future research exploring the neural changes associated of pathological social behavior in mentally ill persons who committed violent crimes.