Differences in Prefrontal Cortex Activation Between Predominantly Positive and Negative Symptom Profiles in Schizophrenia: A Functional Near-Infrared Spectroscopy Study

BACKGROUND Schizophrenia is a heterogeneous disorder characterized by varying degrees of positive and negative symptoms. Rather than relying on outdated categorical subtypes, current research emphasizes dimensional approaches. This study aimed to investigate differences in prefrontal cortex activation between patients with predominantly positive symptom schizophrenia (PSZ) and predominantly negative symptom schizophrenia (NSZ), as defined by the Positive and Negative Syndrome Scale (PANSS)-derived Bipolar Index (PBI). MATERIAL AND METHODS A total of 36 patients with PSZ (PBI>0) and 35 patients with NSZ (PBI<0) were recruited. All patients underwent functional near-infrared spectroscopy (fNIRS) measurements during the verbal fluency task. Hemodynamic changes in the prefrontal cortex were analyzed using a general linear model. The relationship between ß values of specific channels and Brief Psychiatric Rating Scale factor scores was examined. RESULTS The results showed no significant differences in hemodynamic responses between the PSZ and NSZ groups in the different regions of interest. However, channels Ch21 and Ch51 (involving the frontal pole, orbitofrontal cortex, and triangular part of Broca's area) exhibited significant activation differences between the 2 groups after false discovery rate correction. Additionally, the ß value of channel Ch51 was negatively correlated with the activators of the Brief Psychiatric Rating Scale (r=-0.292, P=0.022). CONCLUSIONS This study highlights distinct patterns of prefrontal cortex activation between patients with PSZ and NSZ, particularly in specific channels. These findings support a dimensional approach to schizophrenia heterogeneity and suggest that fNIRS-derived neurobiological markers can inform symptom-specific interventions.