Association Between Occipital Structural And Functional Abnormalities And Clinical Phenotypes In Depression

Background: Major depression disorder(MDD),also known as depressive disorder,is an affective disorder with significant and continuous depression as the core symptom.It is a very common chronic mental disease.At present,the specific neurobiological mechanism ofMDD is not clear.The occipital lobe is the main part of the visual center and the key brain area for processing speech,motor perception and abstract ideas.Abnormal changes of occipital lobe will not only damage visual function,but also interfere with memory and motor perception,and eventually lead to abnormal psychological behavior.Recent studies suggest that the abnormalities of occipital structure and function may be involved in the pathogenesis ofMDD.Previous studies found that there were abnormalities in the occipital lobe,such as reduced gray matter volume,decreased blood perfusion and reduced functional connectivity.However,there are few studies on the relationship between occipital lobe related brain networks and structures and their association with clinical behavior.Therefore,this study will focus on the opening of cerebral gray matter volume,cerebral blood flow and brain function network of occipital lobe,and explore its association with clinical phenotypes,so as to provide basis for revealing the neuropathological mechanism of occipital abnormalities involved in the occurrence and development ofMDD.Association between occipital structure and blood flow abnormalities and clinical phenotypes in depression Objective: Based on magnetic resonance imaging(MRI),this study explored the abnormal changes of occipital lobe structure and blood flow in patients with MDD and the relationship between them and the clinical phenotypes ofMDD.Methods: 66 patients with MDD and 31 healthy controls(HCs)were included in this study.All subjects underwent multidimensional neuropsychological scale evaluation and MRI scanning.According to aal90 template,the occipital lobe was divided into six brain regions:bilateral superior occipital gyrus,middle occipital gyrus and inferior occipital gyrus.All subjects were divided into MDD group and HC group.The changes of gray matter volume(GMV)of occipital lobe were analyzed by voxel based morphometry(VBM).Arterial spin labeling(ASL)was used to analyze the changes of occipital blood perfusion.The changes of occipital structure and blood flow related to MDD were analyzed by two sample t-test.Partial correlation analysis was used to further explore the correlation between these abnormal changes and the clinical phenotypes ofMDD.Finally,receiver operating characteristic curve(ROC)analysis was used to explore the classification effect of occipital lobe abnormalities on MDD population.Results: There were significant differences in occipital structure and blood flow between MDD group and HC group.Compared with HC group,MDD group showed extensive GMV reduction,such as bilateral cerebellum,bilateral temporal lobe,right frontal lobe and some occipital areas.The GMV reduction of left inferior occipital gyrus was negatively correlated with the score of Hamilton Depression Scale(HAMD)in MDD patients.ASL statistical results showed that the cerebral blood flow(CBF)of the right superior occipital gyrus and inferior occipital gyrus in MDD group was lower than that in HC group.This decrease was also negatively correlated with the HAMD score ofMDD patients.ROC analysis showed that the above abnormalities of occipital structure and blood flow had certain significance for MDD classification.The area under the curve(AUC)were 0.704 and 0.652 respectively.Conclusion: The results show that there is a significant decrease in occipital GMV and blood perfusion in patients with MDD.There is a negative correlation between this abnormality and HAMD scores,suggesting that occipital abnormality may be one of the pathological mechanisms of the occurrence and development of MDD.These results provided a research basis for further elucidating the pathogenesis ofMDD.Association between occipital networks and clinical phenotypes in depressionBackground: Childhood maltreatment(CM)experience is a main risk factor of depression and significantly affects the occurrence and development ofMDD.Preliminary studies suggest that CM may affect the abnormalities of occipital structure and function and lead to depression,but the relationship between CM,occipital network abnormalities and depression severity is still unclear.Methods: 97 subjects(66 MDD patients and 31 HC)were included in this study,and their resting state fMRI(rs-fMRI)data were analyzed accordingly.The six brain regions of occipital lobe were used as regions of interest(ROI)to construct functional connectivity(FC),and the occipital functional connectivity(OFC),network pattern characteristics,inter group differences and their correlation with clinical behaviors were analyzed.Two sample t-test was used to compare the inter group differences of six OFC network strength,and partial correlation analysis was used to explore the correlation between different OFC network strength and CM experience and depressive symptoms.Mediation analysis was used to further explore whether OFC network strength can regulate the impact of CM experience on MDD.Finally,graph theory analysis was used to study the occipital network properties ofMDD patients and its relationship with CM experience and depressive symptoms.Results:(1)Compared with HC group,the average OFC strength between right occipital gyrus and left fusiform gyrus,bilateral middle occipital gyrus and parietal lobe,right superior occipital gyrus and right thalamus in MDD patients was lower,which was negatively correlated with CM score and depression severity.(2)Intermediary analysis showed that FC between occipital lobe and bilateral wedge lobe,left angular gyrus and left talus cortex in patients with MDD could regulate the effect of CM severity on depressive symptoms in patients with MDD.(3)Graph theory analysis showed that the global efficiency of occipital network in all subjects was positively correlated with HAMD-weight factor scores,while the shortest path length was negatively correlated with CTQ-sexual abuse score.Conclusion: Compared to HC,there are abnormal changes in occipital networks in patients with MDD.The lower the OFC strength,the more severe the CM experience and depression symptoms.The OFC network strength of overlapping abnormal brain regions which both related to these two clinical phenotypes can positively regulate the relationship between them.Besides,the occipital network properties ofMDD patients also play a compensatory role in the process ofMDD.These results suggested that the abnormal changes of occipital networks are involved in the pathogenesis of MDD.