Brain Structure Abnormalities And Symptom Dimension Relationships In Obsessive-compulsive Disorder : A Diffusional Kurtosis Imaging Study

[Objective] The aims of the present study is to determine gray matter(GM) and white matter(WM) microstructure abnormalities in patients with obsessive-compulsive disorder(OCD) by means of diffusional kurtosis imaging(DKI), and to investigate whether the microstructure changes correlates to the different symptom dimensions.[Method] Whole-brain voxel-based analysis(VBA) was used to compare the diffusional kurtosis imaging(DKI) derived parameters,including mean kurtosis(MK) and fractional anisotropy(FA) between 43drug-na?ve OCD patients and 35 healthy controls. VBA was also used to compare the MK values between the patient with higher and lower scores on Obsessive– Compulsive Inventory – Revised(OCI-R)subscales.[Result]1.Compared with healthy controls, significant increase of GM microstructural complexity was found in left caudate, left cingulate gyrus,right Rolandic operculum, right insula, right precuneus, right superior temporal gyrus(STG), right inferior frontal gyrus(IFG), right supplementary moter area(SMA), right parahippocampal gyrus and bilateral thalamus in OCD patients. Significant increase of WM microstructual complexity was found in bilateral middle temporal gyrus(MTG), left cingulate gyrus, left striatum, right STG, right insula and right precuneus, while FA was increased in left SMA, left MTG, left middle frontal gyrus(MFG) and right precuneus(P<0.001, cluster size≥15 voxels, uncorrected).2. Significant increase of microstructural complexity was found in the thalamus in the OCD patients with higher scores on OCI-R obsessing subscale. Significant increase of microstructural complexity was found in the parahippocampal gyrus and insula in the OCD patients with higher scores on OCI-R washing subscale. Significant increase of microstructural complexity was found in the MTG in the OCD patients with higher scores on OCI-R checking subscale.(P<0.001, cluster size≥15 voxels, uncorrected).[Conclusion]1. The findings suggest increase of GM/WM microstructural complexity at a widespread level in drug-na?ve OCD patients.2. The obsessing symptom was related to the abnormality in the thalamus, while the structure outside the CSTC circuit was related to the expression of different compulsive behaviors, supporting the heterogeneous multi-dimension model of OCD.