| ObjectiveMelancholic depression is considered to be a severe major depressive disorder(MDD).Previous studies have confirmed structural and functional changes of the emotion-related brain regions in patients with melancholic MDD.Therefore,this study aims to study the dynamic functional changes of regional brain areas of melancholic MDD by using amplitude of low-frequency fluctuations(d ALFF)and dynamic fractional amplitude of low-frequency fluctuation(df ALFF),and the changes in dynamic functional connectivity(d FC)between emotion-related brain regions(the bilateral hippocampus,amygdala and insula)and other brain regions,so as to provide neuroimaging biomarkers for patients with melancholic MDD.Our second goal was to explore the relationship between abnormal dynamic indicators and cognitive impairment in the melancholic MDD.MethodsA total of 42 untreated patients with melancholic MDD and 55 healthy controls(HCs)underwent resting-state functional magnetic resonance imaging(rs-f MRI).The subjects who completed the MRI scan were clinically evaluated(initial age,total course of disease,24 item Hamilton Depression Rating Scale e,etc.)and cognitive test using the MATRICS Consensus Cognitive Battery(MCCB)within 24 hours of the MRI scan.The image data were preprocessed,and the sliding window analysis was used to calculate the d ALFF,df ALFF and whole brain d FC of each subregion(bilateral hippocampus,amygdala,insular subregion).A multivariate analysis of covariance was used to compare the cognitive differences between the two groups.Two-sample t-test was used to calculate the differences among d ALFF,df ALFF and d FC.Then,the correlation between the d ALFF,df ALFF and d FC values in different brain regions and patients’ clinical information and cognitive performance was analyzed.Results1.Cognitive comparison: patients with melancholic MDD displayed poorer cognitive scores in information processing speed(F=5.663,p=0.02),working memory(F=9.457,p=0.003),verbal learning(F=14.229,p<0.001),visual learning,(F=9.944,p=0.002)and social cognition(F=28.347,p<0.001)compared with HCs(p<0.05).2.Comparison of d ALFF and df ALFF variability: compared with HCs,patients with melancholic MDD showed increased d ALFF variability in the left anterior lobe of cerebellum;The df ALFF variability of the left anterior lobe of cerebellum and left superior temporal gyrus were increased in patients with melancholic MDD(GRF corrected,voxel-level p <0.005,cluster-level p <0.05).3.Comparison of d FC variability: compared with HCs,patients with melancholic MDD showed decreased d FC variability of the left rostral hippocampus-left anterior lobe of the cerebellum(GRF corrected,voxel-level p <0.005,cluster-level p <0.0125);and decreased d FC variability between the right middle insula and left insula(GRF corrected,voxel-level p <0.005,cluster-level p <0.0083).Additionally,there was no significant difference in d FC based on bilateral am ygdala subregions in melancholic MDD patients compared with HCs.4.Correlation analysis: in melancholic MDD patients,the increased df ALFF variability in the left anterior lobe of cerebellum was positively correlated with HAMD(r=0.352,p=0.028);the increased df ALFF variability in the left insula was negatively correlated with the information processing speed(r=-0.443,p=0.003);the d FC variability values of the left rostral hippocampus-left anterior lobe of the cerebellum was positively correlated with working memory(r=0.338,p=0.029);the verbal learning was negatively correlated with the HAMD scores(r=-0.403,p=0.008).ConclusionPatients with melancholic MDD have abnormal local dynamic functional activities of cerebellum and insula,and abnormal d FC in hippocampus-cerebellum and insula-precentral gyrus,which are related to the severity of depression and cognitive impairment. |
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