| BackgroundObsessive-compulsive disorder with obsessive-compulsive thinking or behavior as its core symptom is a common mental disorder.More than half of the patients with obsessive-compulsive disorder started in childhood,and its pathogenesis has not yet been completely clarified.Compared with adult onset patients,the symptoms of obsessive-compulsive disorder in children and adolescents are more atypical and the treatment effect is worse.At present,most studies have found that obsessive-compulsive disorder involves abnormal brain structure and function.Existing nuclear magnetic resonance studies have found that the integrity of white matter structure and fiber structure in patients with obsessive-compulsive disorder is abnormal,and most of them are concentrated in the cortico-striato-thalamo-cortical.At present,there are few reports on obsessive-compulsive disorder in children.In this study,magnetic resonance imaging（MRI）is used to study the white matter of children and adolescents with obsessive-compulsive disorder（OCD）from two aspects: structural and fiber structural integrity,and analyze its correlation with clinical symptoms,so as to explore the pathophysiological mechanism of OCD in children and adolescents.Objectives1.To analyze the structural characteristics of white matter and the integrity of fiber structure in children with first-episode obsessive-compulsive disorder.2.Analyze the relationship between white matter volume,fiber structure integrity and clinical symptoms in abnormal brain areas of children and adolescents with first-episode obsessive-compulsive disorder.MethodsSubjects: 38 patients with first-episode obsessive-compulsive disorder were selected as obsessive-compulsive disorder group,while 35 healthy children and adolescents whose age,sex,race,education level and other basic information matched with the patient group were selected as the control group.In the process of data analysis,6 patients were excluded after brain white matter structural phase data preprocessing,7 patients were excluded after DTI data processing,and 1 healthy subject data was excluded.Finally,32 patients were included in white matter volume analysis,31 patients were included in DTI data analysis,and 34 healthy control subjects were included in white matter volume and DTI data analysis.2.methods:（1）Evaluation of obsessive-compulsive disorder symptoms: before treatment,two doctors with child psychiatric qualifications used the Yale-Brown obsessive-compulsive scale for children（age range 8-17 years）to assess the severity of obsessive-compulsive symptoms in all subjects.（2）Structural image acquisition and processing: all the subjects were recruited by our hospital,and the structural data were collected by 3.0T magnetic resonance scanning in our hospital.On the Matlab2013 b platform,SPM8 software package VBM8 and REST software package for data analysis.（3）DTI data processing: the FSL software developed by the brain functional Magnetic Resonance Imaging Center of the University of Oxford and the PANDA t oolkit were used for data processing.The linear registration toolkit FNIRT was us ed to register the values of FA,AD and MD of each subject to the MNI standard space.Make average FA,AD and MD templates for all FA,AD and MD value ma ps after registration.The statistically significant brain regions were identified and di splayed by FSLView tool.（4）Correlation analysis: the white matter volume values of obsessive-compulsive disorder group and control group were calculated by REST software through independent sample T test,and multiple comparisons were corrected by Alphasim.The FA,MD and AD values of white matter in obsessive-compulsive disorder group and control group were calculated by independent sample T test with FSL software,and corrected by permutation（P < 0.05,P < 0.01）.The volume of white matter and the values of FA,MD,AD of different brain regions in obsessive-compulsive disorder group were analyzed by Pearson correlation analysis,and multiple tests were performed by Bonferroni correction method.Results1.The results of white matter volume analysis between the obsessive-compulsive disorder group and the control groupCompared with the control group,the brain regions with lower white matter volume in the obsessive-compulsive disorder group were left inferior frontal gyrus,right inferior temporal gyrus,left parietal gyrus,right inferior frontal gyrus and left marginal lobe.（Alphasim correction,t=-3.6737,-4.2127,-3.698,-3.5837,-4.3421;P<0.01）.2.The results of DTI analysis were compared between the obsessive compulsive disorder group and the control group.（1）FA value: FA value of left corticospinal tract and left superior longitudinal tract in obsessive-compulsive disorder group was higher than that in control group（permutation correction,P<0.05）.The lower FA values of white matter in OCD group were corpus callosum radiation occipital part,corpus callosum radiation frontal part,left thalamus anterior radiation,right thalamus anterior radiation,left suboccipital tract,right suboccipital tract,left cingulate gyrus,left lower longitudinal tract,right lower longitudinal bundle and right superior longitudinal bundle（temporal）（permutation correction,P< 0.01）.（2）MD value: compared with the control group,the brain regions with increased MD of white matter in OCD group were left and right corticospinal tract,left and right thalamic anterior radiation,left lower longitudinal tract,left superior longitudinal tract,left and right suboccipital tract（permutation correction,P<0.05）.In OCD group,MD decreased in corpus callosum radiation occipital and corpus callosum radiation frontal（permutation correction,P<0.01）.（3）AD value: compared with the control group,the increased AD values of white matter in the obsessive-compulsive disorder group were in the left and right corticospinal tract,left and right thalamic anterior radiation,left and right frontal suboccipital tract,left superior longitudinal tract and left lower longitudinal tract（permutation correction,P<0.05）.The decreased AD value of white matter in the obsessive-compulsive disorder group was located in the frontal part of the corpus callosum,the occipital part of the corpus callosum,the left uncinate tract and the right superior longitudinal tract（permutation correction,P<0.01）.3.Correlation between FA,MD,AD values and obsessive-compulsive scale scores in differential brain white matter volume and DTI in obsessive-compulsive disorder group（1）Correlation between white matter volume and CY-BOCS score in different brain regions of obsessive-compulsive disorder group: Pearson correlation analysis showed that the right inferior frontal gyrus was negatively correlated with obsessive-compulsive thinking factor scores（r =-0.350,P<0.05）,and the left parietal gyrus was negatively correlated with obsessive-compulsive thinking factor scores,obsessive-compulsive thinking factor scores and obsessive-compulsive behavior factor scores.（r=-0.361,-0.360,-0.376;P<0.05）;After Bonferroni correction,there was no significant correlation between all white matter volume and obsessive-compulsive symptoms.（2）Correlation between FA value of differential white matter and obsessive-co mpulsive scale score in obsessive-compulsive disorder group: Pearson correlation ana lysis showed that corpus callosum radiation occipital was negatively correlated with total obsessive-compulsive score and obsessive-compulsive behavior factor score（r=-0.410,-0.411;P<0.05）;After Bonferroni correction,the correlation between the FA value of corpus callosum radiation occipital and the total score of obsessive-compul sive was still established.（3）Correlation between MD and obsessive-compulsive scale scores in white matter differential brain areas of obsessive-compulsive disorder group: Pearson correlation analysis showed that anterior radiation of left and right thalamus was negatively correlated with total score of obsessive-compulsive disorder（r =-0.446（left）,-0.405（right）,P<0.001）.Anterior radiation of left and right thalamus was negatively correlated with obsessive-compulsive behavior factor scores（r =-0.530（left）,-0.539（right）,P<0.0l）.The left suboccipital bundle was negatively correlated with the total score of obsessive-compulsive thinking and the factor score of obsessive-compulsive thinking（r =-0.416（left）,P < 0.05;r =-0.436（right）,P < 0.01）;After Bonferroni correction,the relationship between the MD value of left anterior thalamus and the total score of obsessive-compulsive thinking was still established,the correlation between MD of left and right thalamus and obsessive-compulsive behavior factor score was still established,and the correlation between right frontal suboccipital tract and obsessive-compulsive thinking factor score was still established.（4）Correlation between AD value and CY-BOCS score in different brain regions of obsessive-compulsive disorder group: Pearson correlation analysis showed that there was a negative correlation between left and right anterior thalamic radiation and obsessive-compulsive total score（r=-0.446（left）,-0.405（right）;P<0.05.）there was a negative correlation between left and right anterior thalamic radiation and obsessive-compulsive behavior factor scores（r=-0.530（left）,-0.539（right）;P<0.0l）.the left suboccipital bundle was negatively correlated with the total score of obsessive-compulsive and obsessive-compulsive thinking factor scores（r=-0.359（left）,P<0.05;r=-0.499（right）;P<0.01）;After Bonferroni correction,the correlation between the AD value of left and right thalamus and the total score of obsessive-compulsive was still established.Conclusions1.In children and adolescents with obsessive-compulsive disorder,there are reduced white matter volume and impaired white matter fiber structural integrity in many brain regions,in addition to the cortical-striatal-thalamic-cortical loop reported in the literature.it also involves many brain regions,such as parietal lobe,marginal lobe,temporal lobe,corpus callosum,corticospinal tract,inferior longitudinal tract and so on.2.This study suggest that abnormal white matter integrity is related to the severity of obsessive-compulsive disorder symptoms,and these brain regions may play an important role in the pathogenesis of obsessive-compulsive disorder. |
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