The Study Of Therapeutic Effects And Associated Mechanism Of Repetitive Transcranial Magnetic Stimulation Over Patients With Mild Cognitive Impairment

Objective: Repetitive transcranial magnetic stimulation(rTMS)is thought to be a potential method to alleviate cognitive symptoms in patients with amnestic mild cognitive impairment(aMCI),but the mechanism related to the network modification is rarely confirmed.Here we tested its efficacy and explored the effect of rTMS-induced changes in the default mode network(DMN)and the predictive value for treatment response.Methods: Twenty-five subjects clinically diagnosed with aMCI were recruited to complete a 2-weeks randomized and sham-controlled rTMS treatment targeting the right dorsolateral prefrontal cortex(rDLPFC).Resting-state functional magnetic resonance imaging(rsfMRI)in tandem with neuropsychological assessments were administered before and after the intervention.Changes in functional connectivity(FC)of the DMN and relevant brain regions,as well as their correlations with clinical rating scales were calculated in order to elucidate the mechanism of treatment response to rTMS therapy.Results: Twenty-one subjects(eight male subjects,thirteen female subjects)finished the rTMS treatment.Two subjects were excluded because of abnormal findings on structural MRI scanning,the other two were excluded because of incomplete course of treatment.Compared to the sham group,the rTMS group achieved improvement of neuropsychological performance and significant functional connectivity changes within the DMN.GroupíTime interactions were found between posterior cingulate gyrus(PCG)and right fusiform gyrus(FFG.R)(F(1,19)=17.154,p=.001)and also left anterior cingulate gyrus(ACG.L)(F(1,19)=3.908,p=.063),showing an rTMS-induced deactivation of functional connectivity within the DMN.Baseline functional connectivity analysis of seeds within the DMN in the rTMS group revealed negative correlation with neuropsychological test score changes.Conclusion: rTMS-induced hypoconnectivity within the DMN is associated with clinical cognitive improvements in patients with aMCI.Further,pre-rTMS baseline functional connectivity of the DMN during resting state may be a predictive factor for rTMS treatment response.