| Objective:By conducting a meta-analysis to determine the effectiveness of multisession transcranial Direct current stimulation on cognitive impairment in Alzheimer’s disease and mild cognitive impairment,we aim to provide a reference for future clinical treatment.Methods:In this study,We systematically searched using subject words and free words in Pub Med,Embase,Web of Science databases,Cochrane Central Register of Controlled Trials China Biomedical Database,China National Knowledge Infrastructure,Wan fang Database,and VIP Database for relevant randomized controlled trials or randomized crossover trial of repeated transcranial electrical stimulation for the treatment of Alzheimer’s disease and mild cognitive impairment published before January 30,2020.Relevant research articles published in English or Chinese and the publication status is published literature.In this meta analysis,The evaluation indicators are test scores about overall cognitive ability and neuropsychological and specific cognitive areas in studies.the data used to assess each study was the explicitly declared primary outcome measure.When the primary outcome was not clearly defined,the first outcome reported in the results section was used.In this study,The meta-analysis was conducted with Rev Man 5.3.0 The Cochrane bias risk assessment tool was used to evaluate the included literature.The heterogeneity across effect sizes was assessed with Q-statistics and the I~2 index in Rev Man combined with the forest map.The Egger test and funnel plot were used to evaluate the publication bias of the included literature.The standardized mean of the effect size was selected.When the P value was less than 0.05,the difference was statistically significant.Results:By searching the database,this meta-analysis finally included 7 articles in the AD group,a total of 208 people,and 8 articles in the MCI group,a total of 682people.A meta-analysis of the cognitive function results in the AD group showed that the cognitive function of patients with mild to moderate AD treated with anode t DCS was significantly improved compared with the control group,and the difference was statistically significant:SMD=0.40,95%CI=(0.12,0.69),p=0.005.A meta-analysis of the cognitive function results of the MCI group showed that:I~2=68%,SMD=0.35,95%CI=(0.17,0.54),p=0.0002,showing a significant statistical difference,but high heterogeneity.A meta-analysis after excluding a highly heterogeneous literature from the sensitivity analysis showed that:SMD=0.26,95%CI=(0.07,0.45),p=0.007,indicating that anode t DCS is better than the control group in the improvement of cognitive impairment.The subgroup analysis of current density and stimulation site in AD group and MCI group showed that the cognitive function of AD group and MCI group was significantly improved when the current density was 0.06m A or the stimulation site was temporal region.Because the number of subgroups included in the literature is small,the results of the subgroup analysis need to be carefully considered.Due to the small literature included in this study,no publication bias assessment was performed.Most of the literatures reported adverse reactions.Common adverse events were:skin redness,tingling,mild burning,pain,nausea,etc.No serious adverse reactions occurred.Conclusion:This meta-analysis suggests that repeated anode t DCS has a positive effect on cognitive dysfunction in AD patients and MCI patients.A current density of0.06 m A and the temporal region of the brain may be more beneficial to the treatment of cognitive function in AD and MCI patients.Repeated t DCS is relatively safe in the treatment of AD and MCI cognitive dysfunction.In the future,a larger sample size and higher quality randomized controlled trials are still needed to further explore the therapeutic effect of repeated t DCS on AD and MCI cognitive function,and to continuously improve t DCS treatment Protocol. |
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