Brain Structure And Function Abnormalities In PTSD And PTSD Comorbid With Major Depressive Disorder Patients Based On Magnetic Resonance Imaging

Part One.Structural magnetic resonance of brain in patients with post-traumatic stress disorder based on voxel morphometryObjectives:To comprehensively explore the brain structural changes in patients with post-traumatic stress disorder(PTSD)after traumatic exposure to car accidents.Methods:46 cases of PTSD patients caused by car accident(PTSD group)and 49 cases of normal healthy people matching gender and age(control group)were selected for MRI scanning.Using Voxel based morphometry(VBM)method to detect the differences in the volume of gray matter or white matter between the two groups.The correlation between the abnormal brain regions and clinical symptoms of PTSD was also studied.Results:Compared with control,gray matter volume in PTSD patients was decreased significantly in the following regions:the left hippocampus,the left postcentral gyrus and the right superior frontal gyrus(voxel P<0.001,cluster P<0.05,two-tailed GRF-corrected),cluster size>100.The gray matter volume in the left postcentral gyrus negatively correlated with the CAPS score of all subjects.Conclusion:This study suggests that the reduction of gray matter volume in the left hippocampus,the left postcentral gyrus and the right superior frontal gyrus is observed in PTSD patients,the volume changes of hippocampus and prefrontal lobe were consistent with previous studies.In addition,PTSD symptom is associated with gray matter density of left postcentral gyrus,suggesting pathological changes in the structure of these brain regions after the trauma of a car accident,which provided the basis of brain structure imaging for the early diagnosis of PTSD.Part Two.Altered resting state functional connectivity of the fear network in patients with PTSD comorbid with major depressive disorderObjectives:Individuals with comorbid post-traumatic stress disorder and major depressive disorder(PTSD+MDD)often exhibit greater neurocognitive impairment and a poorer treatment response than do those with PTSD alone.The underlying pathophysiology is still poorly understood but increasing evidence suggests that the functional connectivity(FC)of the brain regions involved in fear processing is often impaired in individuals with PTSD and MDD.Identifying similarities and differences in fear network connectivity between PTSD patients with and without comorbid MDD can improve our understanding of the pathophysiological mechanisms and develop more effective treatments.This study aimed to compare the resting state whole brain FC patterns of each brain region involved in the fear network between PTSD patients with and without comorbid MDD and healthy controls.Methods:Patients with PTSD+MDD(n=27)or PTSD(n=28)and healthy controls(n=28)were enrolled.We used resting-state functional magnetic resonance imaging(rs-fMRI)to evaluate the resting state FC patterns of the brain regions involved in fear processing.We selected eight regions of interest including the dorsal anterior cingulate cortex,left anterior insula,right anterior insula,ventromedial prefrontal cortex(vmPFC),bilateral amygdala,and hippocampus.Results:The FC of the vmPFC differed among the PTSD+MDD,PTSD and healthy groups.Stronger vmPFC-caudate connectivity was found in the PTSD+MDD group than in the PTSD group,and stronger vmPFC connectivity with the bilateral caudate,Frontal_Sup_L,and Frontal_Mid_R was found in the PTSD+MDD group than in the healthy control group.The PTSD group exhibited stronger vmPFC connectivity with the Frontal_Sup_Medial_L and Frontal_Sup_R relative to the healthy controls.Conclusion:Altered vmPFC-caudate FC can be considered a potential biomarker to distinguish PTSD+MDD from PTSD.The abnormal enhancement between vmPFC and dorsolateral prefrontal cortex may be related to overlapping symptoms of PTSD+MDD and PTSD.As patients with PTSD+MDD are more treatment resistant,these findings can also guide treatment development,such as targeting the vmPFC network.