Neural Mechanism Of The Autistic Children: A DTI And MRS Study

Objective:To research the structures and functions of the white matter in the brain and their correlationwith clinical symptoms in autistic children by DTI and MRS studies, furthermore, explore theneural mechanism of autism from neurophysiology and neurochemistry.Methods:The autism group (n=14) and control group (n=8) were undergone DTI and MRS scan. Wetook the bilateral frontal lobe, hippocampus, the genu and splenium of the corpus callosum andcerebellum white matter as the regions of interest (ROI). We measured FA, ADC value and NAA,Cho, Cr absolute value and NAA/Cr, Cho/Cr ratio. The differences of the above values in thetwo groups and double sides of both groups were analyzed. The correlations between the abovevalues in the autistic group and autism clinical symptoms (ABC and CARS scales), age wereanalyzed.Results:1、Comparison in autism group and control group:DTI Results: autism group exhibited significantly lower FA values in the left hippocampusthan control group (P=0.033).MRS results: autism group exhibited significantly lower Cr values in the left and righthippocampus than control group (P=0.020,0.044).2、Comparison of hemisphere in autism group and control group:DTI Results: autism group exhibited significantly lower FA values in the left genu of thecorpus callosum than the right side (P=0.042), autism group exhibited significantly lower ADCvalues in the left splenium of the corpus callosum than the right side (P=0.006).No significantdifferences were detected between left and right hemispheres’ FA,ADC values in controlgroup(P>0.05).MRS results: autism group exhibited significantly lower NAA, Cho, and Cr in the left frontallobe than the right side (P=0.015,0.015,0.020); autism group exhibited significantly lower NAAvalues in the left splenium of the corpus callosum than the right side (P=0.009); autism groupexhibited significantly lower Cho/Cr ratio in the left cerebellar than the right side (P=0.044). Nosignificant differences were detected between left and right hemispheres’ metabolite levels incontrol group(P>0.05).3、Correlation between clinical symptoms and imaging characteristics in autism group: cerebellum and their CARS scores(r=0.684,P=0.02).MRS results: there was a significant negative correlation between NAA/Cr ratio in the lefthippocampus and their ABC scores(r=-0.729,P=0.003); there was a significant positivecorrelation between Cho/Cr ratio in the right cerebellum and their CARS scores (r=0.548, P=0.042).4、Correlation between age and imaging characteristics in autism group:DTI results: there was a significant negative correlation between the ADC values in leftcerebellum and their ages (r=-0.614, P=0.044).MRS results: there was a significant positive correlation between NAA/Cr ratio in the rightcerebellum and their ages (r=0.613, P=0.020).Conclusions:1、 There may be intrahemispheric neural underconnectivity and interhemispheric neuralunderconnectivity in autistic children. Furtherore, the result that neuroanatomical connectivitydeclines, whose function will decline supports the neural underconnectivity theory.2、The disorder of cerebellum maybe better reflect the severity of the autistic symptoms. Thestructure and function of cerebellum trend to improve with the age in autistic children.