The Neurobiology Of Suicide Attempt In Youth Depressive Disorder Used By Functional Magnetic Resonance Imaging

PART ONE THE LOCAL FUNCTIONAL ACTIVITY OF RESTING STATE FMRI IN YOUTH DEPRESSION WITH SUICIDE ATTEMPTObjective: The purpose of this study was to investigate the relationship between abnormalities involving local brain function and suicidal attempts in depressed young adults,using resting-state f MRI(RS-f MRI).Method: Thirty-five depressed youths with suicidal attempts(SU group),18 patients without suicidal attempts(NSU group)and 47 gender-,age-and education-matched healthy controls(HC)underwent psychological assessment and R-f MRI.The differences in fractional amplitude of low-frequency fluctuation(ALFF)were compared among the three groups.The clinical factors correlated with z-score ALFF in the regions displaying significant group differences were investigated.The ROC method was used to evaluate these clusters as markers to screenpatients with suicidal behavior.Results: Compared with the NSU and HC groups,the SU group showed increased z ALFF in the right superior temporal gyrus(r-STG),left middle temporal gyrus(l-MTG)and left middle occipital gyrus(l-MOG).Additionally,significantly decreased z ALFF values in the l-SFG and l-MFG were found in the SU group compared with the NSU group,which were negatively correlated with BIS scores in the SU group.Further ROC analysis revealed that the mean z ALFF values in these two regions(sensitivity = 83.3% and specificity = 71.4%)served as markers to differentiate the two patient subtypes.Conclusion: Decreased activity in l-SFG and l-MFG resulted in suicidal behavior among depressed youth by increasing impulsivity.Abnormal neural activity in these brain regions may contribute to neurobiological diathesis or predisposition to suicidal behavior.PART TWO THE FUNCTIONAL CONNECTIVITY OF RESTING STATE FMRI IN YOUTH DEPRESSION WITH SUICIDAL BEHAVIORObjective: The aim of this study was to explore the association of abnormal resting state functional connectivity(RSFC)with suicide attempts in youth depression using resting-state f MRI(RS-f MRI).Method: We used seed-based temporal correlation analysis to assess the resting state functional connectivity(RSFC)differences among the three groups.And to investigate the relationship between abnormal functional connectivity and suicide attempt in young depressed adults using spearman correlation analysis.Results: 1.Functional connectivity analysis based on left middle frontal gyrus(L-MFG)found that,the SU group showed decreased RSFC of L-MFG with left superior parietal gyrus(L-SPG)compared to NSU group;and decreased L-MFG RSFC with left cortical areas including the insular cortex,as well as with left superior parietal gyrus compared to HC group.Compared with HC group,NSU group showed decreased RSFC of L-MFG with right middle frontal gyrus(R-MFG)and the inferior frontal gyrus of orbital(R-IFG-orbit),and increased L-MFG RSFC with L-insular.Based on left superior frontal gyrus(L-SFG)functional connectivity analysis reveals that,compared to NSU group,SU groupshowed increased L-SFG RSFC with right superior frontal gyrus(R-SFG),and decreased RSFC of the L-SFG with right anterior cingulate cortical areas(R-ACC)compared to HC group.In addition,NSU group showed increased RSFC of the left frontal gyrus(L-SFG)with left inferior frontal lobe orbit(L-MFG-orbit).2.The correlation analysis indicated that significantly decreased RSFC of L-MFG with L-SPG was negatively associated with SSI scores(r=-0.4056,P=0.0156)and BIS score(r=-0.3498,P=0.0394)in the SU group.Additionally,the L-SFG RSFC with ACC was negatively correlated with BIS score(r=-0.3472,P=0.0410),but there was no association between L-SFG RSFC with ACC with SSI scores(r=-0.2602,P=0.1312).Conclusion: Decreased resting state functional connectivity of left prefrontal cortex with left parietal cortical areas and with right anterior cingulate cortex might be a predictor of suicidal behavior in young depressed patients.PART THREE THE FUNCTIONAL NETWORK CONNECTIVITY OF RESTING STATE FMRI IN YOUTH DEPRESSION WITH SUICIDAL BEHAVIORObjective: To investigate the functional connectivity of brain networks in youth depression with and without suicide attempts using resting-state functional magnetic resonance imaging as well as to better understand the underlying neural mechanism of suicide.Method: We used independent component analysis to identify intrinsically connected neural networks and analyze the the alterations of intra-and internetwork connectivity using independent component analysis(ICA)and functional network connectivity(FNC)analysis.Results: In the present studym,we compared the resting-state activities between the SU?NSU and HC groups in the default-mode,central executive and salience networks as well as correlations among these networks.We found there were significant differences in network connectivity within the default mode network(DMN),salience network(SN)and bilateral frontal-parietal network(FPN)among three groups.Moreover,SU showed significantly decreased internetwork connectivity between anterior default mode network(a DMN,IC14)and salience network(SN,IC12),as well as the right frontal-parietal network(R-FPN,IC16),however,SU exhibited enhanced internetwork connectivity between the SN and the right fronto-parietal network(R-FPN,IC16)compared to NSU.Relative to HC group,the SU exhibited decreased internetwork connectivity between the a DMN and the left fronto-parietal network(L-FPN,IC8)and between the a DMN and the posterior default network(p DMN,IC32),however,they showed increased internetwork connectivity between SN and L-FPN.Besides,the NSU showed decreased functional network connectivity of p DMN with R-FPN.Conclusion: These findings suggest that SU experience large scale reorganization at the level of the functional network.The suicide attempt is correlated with the abnormal functional network connectivity within and between the RSNs,such as DMN,SN and CEN.More importantly,the enhanced internetwork connectivity of the SN and FPN,and decreased internetwork connectivity between DMN and FPN may be the neurobiological marker of suicide at the level of the large-scale brain network.Our findings may provide new insight into the patterns of functional organization in the suicidal depressed patients' s brain.