| Objective:Evaluate the effects of intermittent theta burst stimulation（iTBS）and repetitive transcranial magnetic stimulation（rTMS）on cognitive function in patients with mild cognitive impairment（MCI）using assessment tools such as event-related potential（ERP）and quantitative electroencephalogram（QEEG）.And explore the neurophysiological mechanism of TMS in different stimulation modes.Methods:We conducted a single-blinded randomized sham-controlled trial using TMS over the left dorsolateral prefrontal cortex（DLPFC）.48 subjects with MCI were randomly assigned to iTBS group,rTMS group and sham stimulation group.Each group was stimulated once with 90%RMT.In the iTBS group,the stimulation time was 2S,the interval time was 8S,a total of 600 pulses,and the treatment time was 190 seconds.In the rTMS group,the stimulation frequency was 20 Hz,with a total of 1600 pulses,and the treatment time was 20 min;The sham stimulation group,the coil was rotated 90° around the handle,and the rest of the stimulation parameters were the same as the iTBS group.Each patient was evaluated for cognitive function using the Chinese version of the Montreal Cognitive Assessment Scale（MoCA）and Mini-mental State Examination（MMSE）before treatment.Before and after treatment,the auditory Oddball paradigm was used to detect P300 caused by target stimulation and collect resting state EEG for 6 minutes.After analysis,the changes of P300 amplitude and incubation period and the frequencies of EEG in the brain of MCI patients were compared.Results:Behavioral data showed that after treatment,the correct rate of the number of P300 target stimulation counts in the iTBS group and rTMS group was significantly higher than before treatment,and the differences were statistically significant.the sham stimulation group was compared with before treatment.The accuracy rate did not increase,and the difference was not statistically significant;the false stimulation group showed no increase in accuracy rate,and the difference was not statistically significant.There was no significant difference between the three groups of patients after treatment.ERP results showed that the amplitudes of Cz,CPz,and Pz in the iTBS group increased after treatment,and the differences were statistically significant.The amplitude of Cz and CPz in rTMS group increased significantly compared with before treatment;Compared with the pre-treatment group,the amplitude of the sham stimulation group did not increase,and the difference was not statistically significant.There was no significant difference between the three groups of patients after treatment,but there was a trend of increasing in the sham stimulation group,rTMS group,and iTBS group.There was no significant difference in latency between the three groups before and after treatment.QEEG frequency domain analysis showed that the iTBS group had significantly higher theta power in the frontal,central,temporal and occipital regions than the pre-treatment group.Alpha waves showed increased power in the central,temporal,and occipital regions.However,delta waves significantly decreased in the frontal,temporal and occipital regions,and the difference was statistically significant.Compared with the pre-treatment group,the rTMS group had significantly higher theta waves in the frontal and occipital regions,and the differences were statistically significant;the other frequencies and their corresponding brain regions were not significantly different.Compared with the pre-treatment group,the sham stimulation group had no significant difference in each frequency of each brain region.Comparisons between groups showed that the theta waves in the iTBS group was higher in the central and occipital regions than in the rTMS group,and the difference was statistically significant.Conclusion:iTBS and rTMS can effectively improve the cognitive function of patients with MCI,and the efficacy of iTBS was better than conventional rTMS,which has great advantages and clinical potential.According to the results of QEEG and P300,it was found that the neural electrophysiological mechanisms stimulated by iTBS and rTMS mainly manifested in the enhancement of Alpha and Theta rhythms and the reduction of Delta rhythms in MCI patients.At the same time,it could also increase the P300 amplitude.Then,it improves brain excitability and neural plasticity,thereby improving cognitive function in patients with MCI. |
