265. DISTINCT AND COMMON SUBCORTICAL FUNCTIONAL CONNECTIVITY REVEALED ACROSS THREE MAJOR PSYCHIATRIC DISORDERS

Abstract Background Subcortical nuclei, including thalamus, basal ganglion and hippocampus-amygdala complex, are frequently implicated in abnormal functional connectivity in patients with schizophrenia (SZ), bipolar disorder (BD) and major depressive disorder (MDD). Consistent findings indicate that these subcortical nuclei exhibit increased functional connectivity with default mode network and decreased functional connectivity with salience and executive control networks, representing a transdiagnostic feature across these three major psychiatric disorders. However, few studies have analyzed the functional connectivity between subcortical regions themselves, despite their central roles in brain function. Recent advancements in data driven methods have provided a detailed subcortical atlas, which may enhance detection and uncover the intricate relationship between these regions. Aims & Objectives This study aims to address a key question: What are the common and distinct functional connections between vital subcortical hubs across the three major psychiatric disorders? By answering this, we hope to deepen our understanding of these disorders and identify potential opportunities for novel treatments. Method We utilized resting-state functional MRI data from 800 participants, comprising 200 individuals each from SZ (mean age 34.11 years; SD 9.86), BD (mean age 35.41 years; SD 11.10), MDD (mean age 38.02; years; SD 12.64), and healthy control (mean age 33.63 years; SD 9.28). Using functional connectivity gradient mapping derived from Tian et al. (2020), we parcellated the subcortical regions in one hemisphere into 26 areas, the thalamus (8 regions), hippocampus (5 regions), amygdala (2 regions) and striatum (12 region, including 2 globus pallidus, 3 putamen, 2 nucleus accumbens, and 4 caudate nucleus). For each participant we calculated pairwise functional connectivity matrices and use general linear model to compare connectivity patterns between patient groups and health controls. Results Patients with schizophrenia exhibited significantly increased functional connectivity with intra-striatum and between thalamus, striatum, and limbic network. However, they showed decreased intra-thalamic functional connectivity. People with bipolar disorder demonstrated increased connectivity between thalamus-amygdala and thalamus-striatum but had more pronounced decreases in intra-thalamic connectivity and between the striatum and both the thalamus and hippocampal-amygdala. People with MDD showed no significant increases in subcortical connectivity but exhibited decreased connectivity between the hippocampal-amygdala and striatum. Discussion & Conclusions Schizophrenia and bipolar disorder shared a pattern of intra-thalamic hypoconnectivity, a trait less pronounced in the MDD group of this study. Hypoconnectivity between the striatum and hippocampus-amygdala distinguished mood disorder from schizophrenia, which exhibited increased connectivity in this region. These finding highlight both shared and distinct pathways among the three psychiatric disorders, reflecting underlying neuronal mechanism and their clinical manifestations.