Neuromodulation Of Transcranial Magnetic Stimulation On Cognition And Brain Network Of Mild Cognitive Impairment

Objective:To explore the effect of repetitive transcranial magnetic stimulation(rTMS)on cognitive impairment in patients with mild cognitive impairment(MCI),according to resting state functional magnetic resonance(rs-fMRI).Methods:40 MCI patients and 22 healthy control subjects were recruited from Nanchong Central Hospital and Heping Road Health Service Center of Shunqing District.The MCI patients were randomly divided into real stimulation group(20 subjects)and sham stimulation group(20 subjects).Every subject received rTMS treatment for 10 consecutive days.Neuropsychological scale assessment was performed before treatment,on the 5th day of treatment,and after treatment.rs-fMRI image acquisition was performed before and after treatment.The 10Hz rTMS over left dorsolateral prefrontal cortex(DLPFC)with 90%of the resting motor threshold(RMT),1500 pulses/day for 10 consecutive days was applied in our study.Identical parameters were used in the sham group except for the sham stimulation coil.Comparisons of the neuropsychological scale scores,Amplitude of Low Frequency Fluctuation(ALFF),and functional network connectivity of these two MCI groups before and after treatment were conducted.Results:(a)There was no significant difference in gender,age,education level,smoking history,drinking history,Hamilton anxiety scale(HAMA),Hamilton depression scale(HAMD),Hachinski ischemia index scale(HIS),Instrumental Activity of Daily Living scale(IADL),Function activity questionnaire(FAQ)scores among three groups(P>0.05).(b)Comparison of cognitive function scores at baseline:compared to healthy control group,the performance of MCI group in neuropsychological scales were significantly worse(P<0.05).And there was no significant difference in that between real rTMS group and sham rTMS group(P>0.05).(c)Comparison of cognitive function scores before and after treatment:Mini-Mental State Examination(MMSE),Montreal Cognitive Assessment-Basic(MoCA-B),Auditory Verbal Learning Test(AVLT)(Immediate memory,N4,N5,N7)and Boston.Naming Test(BNT)were significantly increased in real group after 5 days treatment;MMSE,MoCA-B,AVLT(Immediate memory,N4,N5,N7),AFT,BNT were significantly increased and TMT-A/B were significantly decreased in real group after 10 days treatment(P<0.05).AVLT(Immediate memory,N4,N5,N7)and BNT were significantly increased in sham group after 5 days treatment;AVLT(Immediate memory,N4)was significantly increased in sham group after 10 days treatment(P<0.05).(d)Comparison of cognitive function scores after treatment:there was significant difference in MMSE,MoCA-B,AVLT(immediate memory,N4,N5,N7),TMT-A/B between real group and sham group(P<0.05).And there was no significant difference in AFT between these two groups.(e)Comparison of ALFFs value:patients in real group showed increased ALFFs in the right insular cortex,inferior frontal gyrus-opercular part and decreased ALFFs in the left middle occipital gyrus(LMOG),left angular gyrus,left lingual gyrus after 10-day real rTMS intervention;Patients in sham group showed increased ALFFs in the Superior temporal gyrus,bilateral insular cortex and decreased ALFFs in the right middle occipital gyrus,bilateral middle temporal gyrus after 10-day sham rTMS intervention(P<0.05).(f)Correlation analysis:correlation analysis was made between the changes in ALFFs and that in neuropsychological scale scores after rTMS treatment in real stimulation group.The changes of ALFFs in LMOG was significantly correlated with TMT-B alteration(r=0.57,P=0.02),and changes of ALFFs in the left lingual gyrus was significantly correlated with AVLT-N4 alteration(r=-0.58,P=0.02).(g)Functional connectivity analysis:connectivity between posterior cingulate cortex(PCC)and right supramarginal gyrus(RSG)was significantly increased;connectivity between the right fronto-insular cortex(RFC)and RSG was significantly decreased after rTMS treatment in real group.And that was significantly increased between RSG and LMOG,significantly decreased between PCC and LMOG,right lingual gyrus and left inferior temporal gyrus after rTMS treatment in sham group(P<0.05).Compared with sham group,connectivity between LFC and LITG,RFC and LITG,RLG and LMOG in real group was significantly increased and stronger after rTMS treatment.Conclusion:High-frequency rTMS can effectively modulate neural activity and functional network connectivity in cognitive-related brain areas and improve cognitive function of MCI patients,which is mainly reflected in memory,language function,and executive functions.