Dynamic Amplitude Of Low Frequency-fluctuation In First-episode Treatment-naive Major Depressive Disorder Patients : A Resting-state FMRI Study

Objective:Major depressive disorder(MDD)is a high-incidence psychiatric disorder in the world.It is characterized by low mood,cognitive impairment and social dysfunction,and has a high disability and mortality rate.Resting-state f MRI(R-f MRI)has been widely used in the study of MDD.Among them,amplitude of low-frequency fluctuations(ALFF)is considered to be able to reflect the spontaneous neural activity level of brain regions and provide direct information of damaged brain regions,which has become an important method to find the changes of brain function in the resting state.Although there have been many ALFF studies in MDD,most of these studies were limited to focusing on the static characteristics of human brain activity,ignoring the dynamic change characteristics of human brain spontaneous activity in the time dimension.Studies had shown that the human brain responds to internal or external stimuli through dynamic integration and adjustment on multiple time scales.Dynamic amplitude of low-frequency fluctuation(d ALFF)quantifies the neural activity of the brain by measuring the temporal variability of the local neural activity(intrinsic brain activity,i BA)amplitude between voxels,which can reflect the dynamic characteristics of the brain.Therefore,this study intends to use the d ALFF method to explore the dynamic change characteristics of brain activity in MDD patients,fill in the gap of research on MDD brain dynamics,and compare it with static ALFF results to deepen the understanding of the pathogenesis of MDD.Methods:Recruited 70 first-episode untreated MDD patients and 98 healthy controls(HC)who meet the enrollment criteria,ranging in age from 18 to 60 years,to ensure that the gender,age,and education years match between the two groups.Demographic data and clinical information were collected for all subjects,and the clinical symptoms were assessed using the Hamilton Depression Rating Scale 17-item(HAMD-17),followed by R-f MRI scan.After the demographic data,magnetic resonance imaging and clinical scale data are collected,the SPM8 and SPSS 22.0 software packages were used for data processing and statistical analysis.The main steps were as follows:(1)Demographic data and clinical scales collected were analyzed by descriptive analysis,chi-square test and independent sample t-test according to statistical types;(2)The d ALFF and static ALFF data were statistically analyzed by voxel-based analysis method.DPABI software was used to perform two-sample t-test on the two groups of data.Age,gender,years of education and head movement parameter[Mean Frame Displacements(Mean FD)]were taken as covariates.The significance was determined using a Gaussian random field(GRF)correction method with p<0.05,cluster size P<0.05.After correction,the ALFF value difference between the two groups of brain areas was analyzed to compare whether there are significant differences;(3)Partial correlation analysis was performed between the ALFF value of the brain area with significant differences in the MDD group and the HAMD-17 scale score(P<0.05),with age,gender,years of education and Mean FD as covariates.Results:1.There was no statistical significance in age,gender,years of education and Mean FD between MDD group and HC group(t=0.785,χ~2=0.409,t=1.828,t=-0.251,P>0.05).The total score of HAMD-17 in MDD group was significantly higher than HC group,and the difference between the two groups was statistically significant(P<0.001).2.The t-test results of the two samples showed that in the d ALFF analysis,compared with HC group,the d ALFF value in the left superior temporal gyrus was increased in MDD group,while the d ALFF value in bilateral lingual gyrus was decreased.In the static ALFF analysis,compared with the HC group,the ALFF value in the left caudate nucleus increased in the MDD group,while the ALFF value in the bilateral lingual gyrus decreased(P<0.05,GRF corrected).3.Partial correlation analysis showed that the d ALFF value in bilateral lingual gyrus was negatively correlated with the total score of HAMD-17 in MDD group(r=-0.248,P<0.05).Conclusion:1.Studies have shown that first-episode untreated MDD patients have dynamic abnormalities in brain spontaneous activity,mainly manifested in the left superior temporal gyrus and bilateral lingual gyrus regions.2.In both static ALFF and d ALFF analyses,functional changes in the lingual gyrus were found,suggesting that the lingual gyrus is a important brain region in MDD.3.The d ALFF value of lingual gyrus was negatively correlated with the total score of HAMD-17,suggesting that the dynamic variability of lingual gyrus may be an indicator related to MDD symptoms,which has certain significance for the evaluation of the disease.