Structural Magnetic Resonance Imaging Study Of Amygdala Subregions In Patients With Major Depressive Disorder

Objectives:To compare the differences of the volume and the structural covariant connection of amygdala subregions between patients with major depressive disorder and healthy controls,and to further explore the correlation between the different brain regions and the clinical characteristics of patients.To compare the differences of the volume and the structural covariant connection of amygdala subregions between patients with anxious depression,patients with non-anxious depression and healthy controls and its correlation with clinical characteristics of patients.Methods:MRI scan of the head was conducted on 155 first-episode and untreated depressive patients and 178 healthy controls.To segment the amygdala of all subjects and obtain the volume data of each subregion by using the magnetic resonance data processing software-Freesurfer.The 155 MDD patients were divided into anxious depression group(AD)and non-anxious depression group(NAD)according to whether their anxiety/somatization factor score in HAMD-17 was≥7.Multivariate analysis of covariance was used to compare the volume differences of amygdala and its subregions between MDD group and healthy control group,anxious depression group,non-anxious depression group and healthy control group respectively.Partial correlation analysis was made between volume values of subregions with obvious difference and the course of disease,HAMD-17 total score and factor score.To analyze the structural covariant connection of each subregions of amygdala in the MATLAB 2016a.Results:1.There was no significant difference in the total volume of amygdala between depression group and healthy control group(P>0.05).Compared with healthy control group,MDD group showed the reduced volume in left medial nucleus(F=4.549,P=0.034)and left centrocortical complex(F=5.077,P=0.025).Compared with healthy control group,MDD group showed increased covariant connection between left paralaminar nucleus and left basal nucleus/left accessory basal nucleus/right basal nucleus(P<0.05 uncorrected),while decreased covariant connection between left cortical nucleus and left central nucleus,right cortical nucleus and right accessory basal nucleus/right central nucleus/right cortico-amygdaloid transition area(P<0.05 uncorrected).2.There was no significant difference in the volume of total amygdala between anxious depression group,non-anxious depression group and healthy control group(P>0.05).Compared with healthy control group,non-anxious depression group showed the reduced volume in left central nucleus(P=0.012),left cortical nucleus(P=0.012)and left centrocortical complex(P=0.006).Compared with non-anxious depression group,anxious depression group showed the increased volume in left cortical nucleus(P=0.029).There was no significant difference between anxious depression group and healthy control group in the volume of total amygdala and all subregions(P>0.05).Partial correlation analysis showed that the volume of left cortical nucleus in depression group was positively correlated with the anxiety/somatization factor score(r=0.178,P=0.028).Compared with non-anxious depression group,anxious depression group showed increased covariant connection between right central nucleus and left cortico-amygdaloid transition area(P<0.05 uncorrected).Compared with healthy control group,anxious depression group showed increased covariant connection between left paralaminar nucleus and left basal nucleus(P<0.05 uncorrected),while decreased covariant connection between left cortical nucleus and left central nucleus,right cortical nucleus and right central nucleus/right cortico-amygdaloid transition area(P<0.05 uncorrected).Compared with healthy control group,non-anxious depression group showed increased covariant connection between right basal nucleus and left paralaminar nucleus(P<0.05 uncorrected),while decreased covariant connection between right central nucleus and left cortico-amygdaloid transition area/right medial nucleus/right cortical nucleus,right cortical nucleus and right accessory basal nucleus(P<0.05 uncorrected).Conclusions:1.Compared with healthy controls,the first-episode and untreated depressive patients showed the reduced volume in left medial nucleus and left centrocortical complex,and there was no significant difference in the volume of total amygdala on both sides,which suggested that the change of volume of amygdala subregions was lateralized and the structural changes of amygdala subregions may be more sensitive than the whole amygdala in depressive patients.2.Compared with non-anxious depressive patients,anxious depressive patients showed increased volume in left cortical nucleus,indicating that the increase of volume in left cortical nucleus may be a state marker of anxious depression.3.Although it can not be corrected by multiple comparisons,the results of this study showed that the structural covariant connection between amygdala subregions of depressive patients(including anxious and non-anxious depressive patients)have abnormal changes,suggesting that there is abnormal structural cooperative development among amygdala subregions of depressive patients.