Clinical Studies Of Repetitive Transcranial Magnetic Stimulation (rTMS) On Mild Cognitive Impairment

ObjectiveTo explore the effect of repetitive transcranial magnetic stimulation (rTMS) on mild cognitive impairment (MCI).Method24 MCI patients were selected as the rTMS treatment group, which consists of 12 vascular mild cognitive impairment (vMCI) patients, named vMCI group, and 12 non-vascular MCI patients, named MCI group. Then randomly divided these 24 patients into two groups:12 for combined frequency method group (CFM),12 for common method group(CM). Meanwhile, selected 10 healthy volunteers as the normal control group(NC). The CM group with their routine medical treatment were administated rTMS (1Hz,80%RMT,600pulses per day,5 days per week,3 weeks' interal between the two courses,6 courses together). For the CFM group, besides their routine treatment, with rTMS(200pulses,5Hz,90%RMT) given in the prefrontal area, the same stimulation as CM gourd was given in the bilateral temporal regions. EEG, event-related potentials(ERP) P300 and Clinical Memory Scale(CMS) were performed before and after rTMS in all subjects. These results compared among the different groups in different courses, as well as between pre- and post- rTMS treatment.Results1. The CMS Memory quotient(MQ):After the rTMS treatment, we found MQ improved obviously in the rTMS treatment Groups with the comparison of the baseline(P<0.05), whereas it declined in the NC group without significance(P>0.05); The rTMS groups showed the higher MQ variation rate compared with the NC group(P<0.01). Compared among the treatment groups, the variation rate in CFM group was obviously higher than that in the CM group, and the vMCI group obtained higher rate than that in the MCI group (P<0.05).2. The scores of subtests in Clinical Memory Scale:After rTMS treatment, and the scores in subtest of image free recall was obviously lower than the NC group (P<0.05); The scores in subtests of point-to memory, associative learning and recognition meaningless in the vMCI Group showed an noticeable amilioration(P<0.05). The scores in subtests of point-to memory, associative learning and image free recall of CFM group rise obviously after treatment (P<0.05); Compared with the NC group, the variation rate of five subtests scores (point-to memory, associative learning, image free recall, recognition meaningless and portrait character associated memory) had increased in the rTMS treatment group, except the subtests of point-to memory and portrait character associated memory in CM group and image free recall in vMCI group. In the CFM group, the variation rate of four subtests scoers (point-to memory, associative learning, recognition meaningless and portrait character associated memory) was obviously higher than that in the CM group, and the vMCI group higher than the MCI group (P<0.05); The variation rate of point-to memory was the highest in all of five subtests above mentioned (P>0.05).3. Event-related potentials (ERP):After rTMS treatment, patients with the rTMS treatment had significantly shorter latencies of P300 and increased amplitudes of P300 (P<0.05); Compared with the NC group, both the variation rate of latencies and amplitudes had increased in the rTMS treatment groups. Compared among the treatment groups, the variation rate of CFM group was obviously higher than the CM group (P<0.05).4. Relative frequency band power percentage(RFBPP) of EEG:After the rTMS treatment, in the NC group, RFBPP in low frequentcy band(δ-θband) in temporal, parietal and occipital regions increased (P<0.05), whereas in high frequentcy band (a-yband) in frontal, temporal, parietal and occipital regions, RFBPP showed a decrease(P<0.05); In the rTMS Treatment groups, RFBPP of low frequentcy band(δ-θband) in frontal, temporal, parietal and occipital regions declined, in contrast, in high frequentcy band (α-γband) increased. Compared among the different treatment groups, the variation above mentioned in the CFM Group was obviously higher than that in the CM group, the vMCI group higher than the MCI group, and the 6 course higher than the 3 course (P<0.05).The power ratio of a band toθband (the ratio ofα/θ):After the rTMS treatment, in the NC group, the ratio of a/θin temporal region(T6) delined compared with the baseline(P<0.05); In the rTMS treatment groups, the ratio of a/θin frontal, temporal, parietal and occipital regions increased statistically(P<0.05); Compared among the different treatment groups, the change in the ratio of a/θin temporal, parietal and occipital regions in the CFM group was obviously higher than that in the CM group, the vMCI group higher than the MCI group, and 6 course higher than the 3 course (P<0.05).The EEG coherence value(CohV) between bilatral brains:Compared with the normal controls, the MCI patients had lower coherences value in temporal, occipital and parietal regions inθ, a,βandγfrequency band(P<0.05). After the rTMS treatment, in the rTMS treatment groups, the CohV in the corresponding frequentcy band increased in frontal, temporal, parietal and occipital regions, on the contrary, the NC group decreased (P<0.05).Conclusions1. After the rTMS treatment, the CFM group improved more obviously than the CM group, which clues to that combined frequency rTMS is more effective to protect MCI patients from cognitive function declining than rTMS in the frequency of 1Hz.2. After the rTMS treatment, vascular factor involves deeply in the course of the cognitive dysfunction in MCI. Meanwhile, this suggest that there be more effective increasing the possibility of vascular dementia early intervention in the future.3. The effect of rTMS on congnitive function in MCI is related to the treatment duration. The longer the rTMS courses lasted, the better its effects showed.4. After the rTMS treatment, subjects had significantly shortened latencies of P300 and increased amplitudes of P300, which proved objectively that rTMS treatment can improve the cognitive function in MCI patients.5. The rTMS could decrease the RFBPP in low frequentcy band(δ-θband) power and increase in high frequentcy band(α-yband) power, furthermore, the rTMS could increase the coherence value in the corresponding band. This suggested that rTMS treatment could delay the declining of cognitive function in MCI. To a certain extent, rTMS could play a meaningful role to resist normal aging in the normal people. In other word, rTMS has a positive effect on memory function in healthy persons who might suffer from MCI.