Network Homogeneity Analysis Of Bipolar Disorder:a Resting State Functional Magnetic Resonance Imaging Study

Bipolar Disorder(BD)is a severely disabling,chronic mental illness that affects 1%to 4% of the world’s population.No matter what phases of bipolar disorder they are in:mania,depression,or remission,patients have severe cognitive impairments that have a significant adverse impact on their lives and functions.However,since the exact pathophysiology and biological underpinnings of bipolar disorder remain unclear,it is often misclassified or overdiagnosed.The development of biomarkers for this disorder becomes an urgent question.This study used resting-state functional magnetic resonance imaging(rs-f MRI)technique to compare the functional connectivity of the dorsal attention network and ventral attention network between patients and healthy controls,with the method of network homogeneity(NH)and to explore the implications of the results.Methods: Resting-state f MRI scans were performed on 52 patients with bipolar disorder and 51 healthy controls matched to patients.The collected data are processed as follows: First,the masks of the ventral attention network and the dorsal attention network are obtained through group-level ICA analysis,and then the network homogeneity method(NH)is used to produce the NH maps of the two attention networks for comparison.A correlation analysis is also conducted between the NH of the abnormal brain areas and the scores of Hamilton Depression Scale-17,Perceived Deficit Questionnaire-depression and Young manic rating scale.Then the support vector machine(SVM)machine learning algorithm was used to explore the feasibility of using the NH of brain regions to distinguish bipolar disorder and healthy population at the individual level.Results: compared with healthy controls,significantly decreased NH in the right inferior temporal gyrus and right middle temporal gyrus and increased NH in the right superior marginal gyrus were found in patients with bipolar disorder.There was no correlation between NH in the brain regions mentioned above and clinical symptoms.NH in the right inferior temporal gyrus and middle temporal gyrus showed accuracy higher than 60%.It is found that abnormal NH values existes in the nodes of ventral and dorsal attention network in patients with bipolar disorder,which has the potential to become a biomarker.This study also contributes new evidence of the participation of the altered NH of the dorsal attention network and ventral attention network in the pathophysiology of BD.and provides evidence for the lateralization of neural mechanism of bipolar affective disorder.