Blunted niacin skin flushing response in violent offenders with schizophrenia: A potential auxiliary diagnostic biomarker.

Schizophrenia (SZ) is associated with an increased risk of violence, with clinical diagnosis primarily relies on symptomatology. The niacin skin flushing response (NSFR) is proposed as a potential biomarker for SZ, but its effectiveness in violent offenders with schizophrenia (VOSZ) remains unevaluated. This study investigates whether the diagnostic model differentiating general SZ patients (GSZ) from healthy controls (HCs) using NSFR can also distinguish VOSZ from HCs. SZ patients were continuously sampled based on the International Classification of Diseases, 10th Edition, and categorized into VOSZ (with a history of violent crimes), and GSZ (without such history). HCs had no psychiatric illnesses or violent crime history. A total of 315 VOSZ, 296 GSZ, and 281 HCs were recruited. Least absolute shrinkage and selection operator regression was used to select variables and construct diagnostic models based on NSFR. No significant differences in age, sex or BMI were observed among groups. Both VOSZ and GSZ exhibited similar blunted NSFR compared to HCs. The diagnostic model constructed by 14 NSFR variables distinguishing GSZ from HCs was successfully transferred to distinguish VOSZ from HCs, with areas under the curve of 0.796 (specificity = 81.6%, sensitivity = 64.2%) and 0.798 (specificity = 80.0%, sensitivity = 70.2%), respectively. Moreover, NSFR was unrelated to illness severity, violence, or antipsychotic dosage in VOSZ, suggesting it is a trait indicator of SZ. This study supports the NSFR as an objective diagnostic biomarker for distinguishing VOSZ from HCs, expanding its applicability, although it may not specifically identify violent offenders among SZ patients.