Magnetic Resonance Brain Structural Imaging Study Of Sex Differences In Depression Based On Surface Morphometry

Part one: Gender difference of gray and white matter surface area in major depressive disorderObjective: The purpose of present study was to explore the sex differences in gray and white matter surface area of major depressive disorder(MDD)patients and the relationship between these differences and clinical manifestations in different gender.Methods: High resolution 3DT1 WI data were collected of 61 MDD patients and 61 matched healthy controls(both groups were 25 males and 36females)prospectively.Free Surfer software was used to pre-process the 3DT1 data and obtained the gray and white matter surface area images of all brain regions.Two-factor ANCOVA model was used to analyze the differences of the surface area on gray and white matter among four groups and then post-hoc test was used to analyze the brain regions with differences between every two groups.Correlation analysis was used to analyze the gender differences regions of MDD and their clinical characterisitics.Results: The main effect of sex difference in the surface area of gray and white matter was located in bilateral superiorfrontal gyrus,middletemporal gyrus,left rostralmiddlefrontal gyrus,lateraloccipital gyrus.In addition,the white matter surface area of bilateral superiortemporal gyrus,left precentral gyrus,insular,right parstriangularis gyrus,medialorbitofrontal gyrus,fusiform gyrus,inferiorparietal gyrus,and the gray matter surface area of left supramarginal gyrus,right rostralmiddlefrontal gyrus,precentral gyrus,inferiortemporal gyrus,fusiform gyrus,rostralanteriorcingulate gyrus,lateraloccipital gyrus and inferiorparietal lobule also exhibited gender differences(P<0.01,Bonferroni correction).Post-hoc test showed that the surface area of the above brain regions in female MDD group was smaller than that in male MDD group(P<0.01,Bonferroni correction).Correlation analysis found that the gray matter surface area of right rostralmiddlefrontal(r=-0.398,P=0.049)and fusiform gyrus(r=-0.440,P=0.028)were negatively correlated with the HAMD scores,and the gray matter surface area of left middletemporal gyrus was negatively correlated with the illness duration in male MDD patients(r=-0.419,P=0.037).Conclusion: There are gender differences of gray matter and white matter surface area between male and female MDD patients,but the brain regions do not completely overlap suggesting that gray matter and white matter surface areas have relatively independent neurobiological characteristics.Some of the gray matter surface area related to HAMD score suggesting gray matter surface area can better reflect the disease characteristics of depression than white matter surface area.Part two: Gender difference of brain cortical thickness and surface area in major depressive disorderObjective: The purpose of present study was to explore the sex differences in brain cortical thickness(CT)and surface area(SA)of major depressive disorder(MDD)patients and the relationship between these differences and clinical manifestations in different gender.Methods: High-resolution T1-weighted images was acquired from 61 MDD(36 female [F] and 25 male [M])and 61(36 F and 25M)healthy control(HC).Free Surfer software was used to pre-process the T1 WI data and obtained the CT and SA images of all brain regions.The differences of CT and SA among four groups was analyzed by two way ANCOVA model.Post-hoc test was used to compare the differences of CT and SA between every two groups.Correlation analysis was used to analyze the gender differences regions of MDD and their clinical characterisitics.Results: The main effect of sex difference in CT was located in bilateral precentral gyrus,inferiortemporal gyrus,right superiorfrontal gyrus and superiorparietal gyrus(P<0.05,Vertex correction).While the main effect of sex difference in SA was located in bilateral superiorfrontal gyrus,rostralmiddlefrontal gyrus,middletemporal gyrus,lateraloccipital gyrus,left supramarginal gyrus and right precentral gyrus,inferiortemporal gyrus,fusiform gyrus,rostralanteriorcingulate gyrus(P<0.01,Bonferroni correction).Post-hoc showed that the CT of right precentral gyrus,inferiortemporal gyrus of male MDD was thinner than that in the female MDD group.The SA of the above brain regions in female MDD group were smaller than that in male MDD group(P<0.05,Bonferroni correction).In male MDD patients,the CT of right precentral gyrus(r=-0.481,P=0.015)and the SA of left middletemporal gyrus (r=-0.419,P=0.037)were negatively correlated with the illness duration,while the SA of right rostralmiddlefrontal(r=-0.398,P=0.049)and fusiform gyrus(r=-0.440,P=0.028)were negatively correlated with the HAMD score.Conclusion: There are gender differences in CT and SA between male and female MDD patients.The different brain regions of CT and SA in MDD patients of different gender confirmed the genetical and phenotypical independence of CT and SA,which may be related to the different clinical manifestations and morbidity in male and female MDD patients.