Study Of The Neurological Mechanism Of Tai Chi Combined With TDCS On Cognitive Function In Patients With MCI Based On Multi-modal MRI

Objectives: 1 To evaluate the effects of regular Tai Chi combine with tDCS on the cognitive function and different areas of the cognitive function im MCI patients.2 To explore the potential mechanism of Tai Chi combined with tDCS in improving cognitive function of MCI patients by observing the changes of functional connections and gray matter structure before and after intervention.Methods: Study 1: This study is a parallel randomized controlled clinical trial study,involving 156 qualified subjects and randomly divided into four groups: Tai Chi + tDCS group(n=39),Tai Chi + sham tDCS group(n=39),walking + tDCS group(n=39)and walking + sham tDCS group(n=39).tDCS intervention was performed for the first 20 minutes of Tai Chi or walking training,3 times a week for 12 weeks.Anode tDCS positioning on the right side the dorsolateral prefrontal cortex(DLPFC),true/sham stimulation intensity to 2 mA,for 20 min and 30 s respectively.The Montreal Cognitive Assessment(MoCA),Test of Attentional Performance(TAP)2.3,and Stroop color word test were performed to evaluate the global cognitive function,attention and executive function,respectively at pre-and postintervention.Study 2: Based on the experimental design of study 1,functional MRI scans were performed on subjects without contraindications to NMR before and after the intervention,and structural images of subjects T1 and resting state functional images were collected.In accordance with the template of Anatomical Automatic Labeling(AAL),bilateral hippocampus,left hippocampus and right hippocampus were selected as seed points to conduct functional connection analysis based on Region-of-Interest(ROI),and observe the changes of functional connection between hippocampus and other brain regions before and after intervention in four groups of patients.The correlation between cognitive function change and functional connectivity change was analyzed by partial correlation analysis.Study 3: Based on the experimental design of study 2,brain regions with significantly different functional connections were extracted as regions of interest,performing ROI-based Voxel-based Morphometry(VBM),and extracted participant-specific raw gray matter volumes(GMV)from the smoothed gray matter images for all voxels within each ROI,the changes of brain structure before and after intervention were observed.Combined with cognitive function test data,partial correlation was used to analyze the correlation between cognitive function changes and gray matter changes.Results: 1 Before the intervention,there were no significant differences in age,hand,smoking,drinking or exercise between the four groups(P>0.05).The difference in gender and years of education was statistically significant(P< 0.05).And there were no significant differences in the total scores of MoCA,Stroop tests(P>0.05).After the intervention,the MoCA total score of Tai Chi + tDCS group was significantly higher than that of Tai Chi + sham tDCS group and walking + sham tDCS group(P<0.05).The MoCA-abstract thinking evaluation score of Tai Chi + tDCS group,walking + tDCS group and walking + sham tDCS group were higher than that of Tai Chi + sham tDCS group.The reaction time of Tap-response without warning in Tai Chi +tDCS group was significantly lower than that in the other three groups(P<0.05).Tai Chi +tDCS group and Tai Chi + sham tDCS group showed significantly lower reaction time required for Tap-go/no-go than that for walking +tDCS group(P<0.05).2 The results of the functional connection between the bilateral hippocampus and the whole brain showed that: compared with the Tai Chi+tDCS group and the walking+sham tDCS group,the brain areas with significant differences included the right anterior cingulate gyrus(ACC),right medial prefrontal cortex(mPFC),right inferior occipital gyrus,bilateral cerebellum and right lingual gyrus.Compared with walking +tDCS group and walking + sham tDCS group,the brain areas with significant differences include right middle temporal gyrus,left inferior temporal gyrus,bilateral parahippocampal gyrus,right amygdala,right fusiform gyrus and right temporal pole.There was no significant difference between the two groups.3 The results of functional connection between the left hippocampus and the whole brain showed that the brain regions including the bilateral mPFC and the right suboccipital gyrus were significantly different in the Tai Chi+tDCS group compared with the walking+tDCS group.Compared with the walking+sham tDCS group,the Tai Chi+tDCS group showed significant differences in brain regions including bilateral fusiform gyrus,bilateral lingual gyrus,bilateral cerebellum,and right suboccipital gyrus.Compared with the walking+tDCS group and walking+sham tDCS group,the brain area including the right upper iliac crest,the left inferior temporal gyrus,the bilateral frontal pole,the right temporal iliac crest,and the right amygdala,right hippocampus,right hippocampus,right posterior temporal gyrus,left dorsolateral prefrontal cortex.Compared with the other groups,there was no significant difference in brain regions.4 The results of the functional connection between the right hippocampus and the whole brain showed that the brain regions including the right lateral lobed cortex and bilateral lingual gyrus were significantly different in the Tai Chi+tDCS group compared with the walking+sham tDCS group.Compared with the walking+tDCS group and walking+sham tDCS group,the brain area including the right iliac crest,the right iliac crest,the bilateral bungee,the bilateral fusiform gyrus,the left hippocampus,and the right Side hippocampus.Compared with the other groups,there was no significant difference in brain regions.5 Correlation analysis showed that there was a significant positive correlation between the total score of MoCA and the bilateral hippocampus-right ACC after intervention(r=0.289,P=0.046);There was a significant negative correlation between the total difference of MoCA and the functional connection between the left hippocampus and the bilateral mPFC before and after intervention in the Tai Chi+tDCS group and the walking+tDCS group(r=-0.430,P=0.046).6 Based on the results of ROI functional connection analysis,the right anterior cingulate gyrus and the bilateral medial prefrontal cortex were extracted into the region of interest.Based on ROI-VBM analysis,the right anterior cingulate gyrus and bilateral medial prefrontal cortex GMV were extracted before and after intervention..The comparison of the right ACC GMV in the four groups showed that there was a significant difference between Tai Chi + tDCS and walking+sham tDCS(P<0.001);there was a significant difference between Tai Chi+sham tDCS compared with walking+tDCS(P=0.048);Tai Chi+sham tDCS was statistically different from walking+sham tDCS(P<0.001);walking+tDCS was statistically different from walking+sham tDCS(P=0.001).7 The comparison of GMV in bilateral medial prefrontal cortex between the four groups showed that there was a statistical difference between the Tai Chi+tDCS group and the Tai Chi+sham tDCS group(P<0.001).There was a statistical difference between the Tai Chi+tDCS group and walking+tDCS group(P<0.001);Tai Chi+tDCS was statistically different from walking+sham tDCS(P=0.017).8 Correlation analysis showed that there was no significant correlation between the total score of MoCA and the GMV of right ACC and bilateral mPFC after intervention(P>0.05).Conclusion: 1 Tai Chi with tDCS for 12 weeks can improve the global cognitive function and attention performance of MCI patients.2 12 weeks of Tai Chi combined with tDCS intervention can cause functional connectivity changes in bilateral hippocampus-right ACC,and the change in global cognitive function is related to the functional connection between the bilateral hippocampus-right ACC.