525. ALTERED AUDITORY NETWORK FUNCTIONAL CONNECTIVITY IN PSYCHOTIC DISORDER NOT OTHER SPECIFIED

Abstract Background Psychotic disorder not otherwise specified (PNOS) is used to categorize psychosis cases that do not meet criteria for specific disorders like schizophrenia or bipolar disorder. Among its subtypes, Other Specified Schizophrenia Spectrum and Other Psychotic Disorder (OSSO) has been understudied, particularly regarding its neural mechanisms. Auditory hallucinations (AHs), a common symptom in psychotic disorders, are linked to disruptions in auditory-related brain regions, but their role in OSSOs remains unclear. Aims & Objectives This study aimed to examine functional connectivity (FC) patterns in auditory regions (superior/middle temporal gyrus, Heschl’s gyrus, temporal pole, insula) among OSSOs, schizophrenia spectrum disorders (SSDs), and healthy controls (HCs). The goal was to identify distinct neural mechanisms underlying AHs and their relationship to symptom severity. Method Resting-state fMRI data were collected from 254 participants (88 OSSOs, 81 SSDs, 85 HCs). Seed-based and network-based FC analyses focused on auditory networks. Group comparisons were conducted using ANCOVA, and correlations between FC alterations and psychotic symptoms were assessed with PANSS scores. Results OSSOs exhibited increased FC between the middle temporal gyrus and thalamus/angular gyrus and decreased FC between the insula and putamen compared to HCs, indicating altered sensory processing. SSDs showed increased FC between the superior temporal gyrus and precuneus, reflecting impaired self-referential processing. Direct comparisons revealed reduced FC between the superior temporal gyrus and precuneus in OSSOs relative to SSDs. Correlation analyses linked FC alterations in auditory-related regions with hallucination severity in both OSSOs and SSDs. Discussion & Conclusions Distinct FC patterns in OSSOs and SSDs highlight unique neural mechanisms underlying AHs. Increased thalamic connectivity in OSSOs may reflect compensatory mechanisms for sensory disruptions, while SSDs demonstrate broader disruptions in sensory and self-referential integration. These findings suggest FC alterations as potential biomarkers for psychosis subtypes and emphasize the need for refined diagnostic frameworks and targeted interventions to improve clinical outcomes.