570. A study on the similarities and differences in brain functional connectivity alterations in schizophrenia and bipolar disorder
Abstract Background Schizophrenia (SZ) and bipolar disorder (BD) are common severe mental disorders. Although clear diagnostic boundaries exist between the two disorders, they share overlaps in certain clinical symptoms and abnormal brain network functions. Recent neuroimaging studies have shown both specific differences and common alterations in resting-state brain network functional connectivity (FC) between SZ and BD. However, direct or indirect comparative studies on the similarities and differences in whole-brain functional connectivity patterns between SZ and BD remain limited. This study aims to explore the abnormal functional connectivity features of SZ and BD using both network-level and edge-level functional connectivity analysis methods, providing insights into their neural underpinnings. Aims & Objectives Based on resting-state functional magnetic resonance imaging (fMRI) data from a Chinese population, this study compares brain functional connectivity patterns among SZ, BD, and healthy controls (HC) at both network-level and edge-level analyses. It investigates the specificity and commonality of brain network functional connectivity abnormalities in the two disorders and preliminarily explores the relationship between abnormal functional connectivity and clinical symptoms as well as cognitive impairment. Method A total of 45 SZ patients, 50 BD patients, and 57 HC participants were included in this study. General demographic information, clinical data, and resting-state fMRI data were collected. Network-level functional connectivity analysis was used to compare connectivity features within and between large-scale brain networks among the three groups. Logistic regression was employed to evaluate the predictive performance of functional connectivity features in distinguishing between the two disorders. Edge-level functional connectivity analysis was conducted for pairwise comparisons among SZ, BD, and HC to reveal whole-brain connectivity differences. Correlation analysis was performed to explore the relationship between abnormal edge-level functional connectivity indicators and clinical and cognitive symptom scores in SZ and BD. Results Both SZ and BD exhibited significant FC reductions within and between multiple brain networks, with SZ showing more extensive and severe FC abnormalities. In terms of differences in brain network connectivity abnormalities between SZ and BD, abnormal connectivity within the limbic network (LN) was a key feature distinguishing SZ from BD. Edge-level functional connectivity analysis revealed significant differences in the extent of impairment within the visual network (VN) between the two disorders. In terms of shared abnormal network patterns, weakened connectivity within the dorsal attention network (DAN) may serve as a potential indicator for distinguishing SZ and BD from HC. Networks commonly impaired in both disorders included the sensorimotor network (SMN), VN, and default mode network (DMN). The most significant FC reductions in both disorders were observed in the VN-SMN edges. In SZ, FC strength in the frontoparietal network (FPN)-DMN was significantly positively correlated with visual learning. Discussion & Conclusions Both SZ and BD exhibit abnormal reductions in resting-state brain network connectivity. Differences in limbic network connectivity hold potential diagnostic value for distinguishing between the two disorders, while attention network abnormalities reflect a shared pathological pattern. Additionally, some connectivity features are closely associated with cognitive function.