Resting-state Brain Function Of Major Depressive Disorder With Somatic Symptoms

Objective: To investigate the resting-state brain function in major depressive disorder(MDD)with diurnal rhythms(morning worsening)/somatic symptoms using resting-state functional magnetic resonance imaging,which may help to explore the neural pathological basis of depression subtype with specific biological symptoms.Methods: Patients who met the diagnostic criteria for MDD according to the fourth edition of the Diagnostic and Statistical Manual of Mental Disorders were recruited.Patients were grouped according to the presence or absence of specific biological symptos:(1)diurnal rhythm: patients who scored ?1 in diurnal variation of the 24-item Hamilton Rating Scale for Depression(HAMD24)were defined as depression with diurnal rhythm(diurnal group),and those who scored 0 were defined as depression without diurnal rhythm(non-diurnal group);(2)somatic symptoms: patients with four or more somatic symptoms including fatigue,pain,diurnal rhythm,heart palpitations and dyspnea,sleep disturbances,anorexia,were defined as depression with somatic symptoms(somatic group),and those with less than three abovementioned somatic symptoms were defined as depression without somatic symptoms(non-somatic group).At the same time,healthy volunteers(control group)with matching general conditions such as gender,age,and education level were recruited.All subjects underwent a 3.0T resting state functional magnetic resonance scan.The obtained brain imaging data were preprocessed,which included format conversion,head motion correction,time correction,and normalization.Then imaging data were analyzed from the following aspects:(1)Brain function of depression with diurnal rhythm in resting-state: 1)From the perspective of local brain function,the amplitude of low frequency fluctuation(ALFF)method was used to investigate the energy of brain activity of depression with diurnal rhythms.2)From the perspective of coordination between local brain regions and whole brain,the method of functional connectivity(FC)was applied to explore the synchronization between the suprachiasmatic nucleus(SCN)and whole brain in depression with diurnal rhythm.(2)Brain function of depression with somatic symptoms in resting-state: 1)From the perspective of local brain function,regional homogeneity(Re Ho)method was used to explore the synchronization of regional brain activity in depression with somatic symptoms.2)From the perspective of coordination between local brain regions and whole brain,FC method was used to explore the synchronization between the insulaand whole brain in depression with somatic symptoms.In each part of the experiment,one-way analysis of variance was performed among three groups,which were followed by post-hoc two samples t-tests.Multiple corrections were performed using the Alphasim method to obtain the significantly different brain regions.The Pearson correlation analysis was performed between the characteristics of brain region showing significant difference and the total score of the 17-item Hamilton Rating Scale for Depression(HAMD17)and factor scores.Results:(1)Brain function of depression with diurnal rhythm in resting-state: 1)At the regional brain activity level,ALFF value of the parahippocampal gyrus in the rhythm group was increased compared with the non-rhythm group.When compared with the control group,ALFF value of the right parahippocampal gyrus and the left parietal lobe increased,and ALFF value of the cerebellum decreased;ALFF value increased in the left parietal lobe and decreased in the cerebellum in non-rhythm group.2)At the coordination level between local brain regions and whole brain,the rhythm group showed higher FC between the left SCN and the left inferior orbitofrontal gyrus and left putamen,and lower FC between the right SCN and the right paracentral gyrus,compared with the non-rhythm group and the control group.FC between the left SCN and the left parietal lobe/angular,and between the right SCN and the right postcentral/paracentral gyrus in the non-rhythm group.Negative correlation was found between FC values of the left SCN and the left putamen and the sleep disturbance factor of HAMD17 in rhythm group.(2)Brain function of depression with somatic symptoms in resting-state: 1)At the coordination level within regional brain activity level,Re Ho values in the right middle frontal gyrus and the left precentral gyrus was lower in somatic group compared with non-somatic group.Compared with the control group,Re Ho values of the parahippocampal gyrus and the left lingual gyrus increased while Re Ho decreased in the right middle frontal gyrus in the somatic group;Re Ho in the left hippocampus and the left precentral gyrus of the non-somatic group increased.Moreover,in the somatic group,Re Ho value in the left precentral gyrus was positively correlated with the cognitive impairment factor of HAMD17.2)At the coordination level between local brain area and whole brain,FC decreased between the insula and several right frontal brain regions(such as superior frontal gyrus,superior orbitofrontal gyrus and rectal gyrus),cingulate gyrus,and precuneus in somatic group.Non-somatic group showed increased FC of the ventral anterior insula and the bilateral orbitofrontal cortex.In the somatic group,FC values of the left ventral anterior insula and the right rectus were positively correlated with the cognitive impairment of the HAMD17,FC value of the right ventral anterior insula and the total score of the HAMD17 and cognitive impairment scores were also positively related.Conclusion: MDD patients with diurnal rhythm/somatic symptoms show abnormalities in regional brain activity intensity and synchronization,and synchronization of local brain regions with other brain regions in resting state.These abnormal brain function may be potential neuropathological basis of various somatic symptoms in depression.