Resting-state Amplitude Of Low-Frequency Fluctuations Changes Across Three Mood States Of Bipolar Ⅰ Disorder

Objective: To investigate resting-state Amplitude of Low-Frequency Fluctuations in patients with bipolar I disorder in different mood states,explore the differences and similarities in the brain function of patients with bipolar I disorder in the three clinical phases,and search for possible imaging markers of bipolar I disorder.Methods: This is a cross-sectional study involving 80 patients who met the diagnosis criteria of bipolar I disorder in DSM-Ⅳ-TR and 110 healthy controls.Including 29 patients with bipolar depression(BD-D),25 patients with bipolar mania(BD-M),26 patients with bipolar euthymia(BD-E).The severity of depression and mania were assessed by the Hamilton Depression Scale(HAMD-17)and Young Mania Rating Scale(YMRS).Resting-state f MRI data were obtained and pre-processed.The Amplitude of Low-Frequency Fluctuations(ALFF)values were computed,and analysis of one-way analysis of variance was performed on ALFF values among the four groups.Post hoc analysis was conducted based on the ALFF values extracted from the brain regions with significant differences.GRF(Gaussian Random Field,GRF)correction was used to correct the results(voxel p<0.005,cluster p<0.05).Results:(1)The difference of ALFF value between BD-I group and HC group was found in bilateral fusiform gyrus,parahippocampal gyrus,insula,cuneus and right middle occipital gyrus.(2)Compared with HC group,the ALFF value in the left fusiform gyrus and parahippocampal gyrus were increased in BD-D group,but decreased in the bilateral cuneus.Compared with HC group,the ALFF values in the right fusiform gyrus,orbitofrontal cortex and middle occipital gyrus were increased in BD-M group,but decreased in the bilateral precuneus.Compared with HC group,the ALFF values of BD-E increased in the left fusiform gyrus,parahippocampal gyrus,right orbitofrontal cortex and bilateral insula,but decreased in the right posterior central gyrus,bilateral anterior central gyrus,paracentral lobules and cuneus.(3)No significant difference was found between BD-D group and BD-M group.The ALFF value in the right anterior central gyrus of the BD-E group was decreased than that in the BD-D group,and the ALFF value in the right insula lobe was increased.Compared with BD-M group,the ALFF values in the bilateral insula and precuneus were higher in BD-E group,while the ALFF values in the right middle occipital gyrus were lower.Results:(1)Bipolar I disorder is characterized by ALFF changes in the cuneus and fusiform gyrus across different mood states,suggesting that the cuneus and fusiform gyrus may be symbolic imaging markers of bipolar I disorder.(2)The abnormal mood states of BD-I(depressive and manic)showed abnormal ALFF value in insula compared with the remission mood state,but no significant difference was found between BD-D and BD-M,suggesting that insula may be an imaging marker to distinguish the onset and remission of BD-I.(3)Compared with healthy controls,bipolar I patients showed dysfunctions in brain regions,including the right middle occipital gyrus,orbitofrontal cortex,anterior central gyrus,posterior central gyrus,and paracentral lobule,all of which are related to visual perception,processing,and transmission,suggesting that visual dysfunction may be an important part of the pathophysiological mechanism of BD-I.