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SYSTEMATIC REVIEW article

Front. Hum. Neurosci.
Sec. Brain Imaging and Stimulation
Volume 18 - 2024 | doi: 10.3389/fnhum.2024.1436448

The effects of repetitive transcranial magnetic and transcranial direct current stimulation on memory functions in older adults with mild cognitive impairment: A systematic review and meta-analysis

Provisionally accepted
Mengdie Hu Mengdie Hu 1Michael A. Nitsche Michael A. Nitsche 2*Yanxin Lv Yanxin Lv 3*Hairong Han Hairong Han 4*Xu Lin Xu Lin 5*Fengxue Qi Fengxue Qi 3*
  • 1 School of Sports Medicine and Rehabilitation, Beijing Sport University, Beijing, China
  • 2 Department of Psychology and Neurosciences, Leibniz Research Centre for Working Environment and Human Factors, Dortmund, Germany
  • 3 Sports Coaching College, Beijing Sports University, Beijing, China
  • 4 Blood purification Department, The Eighth People’s Hospital of Jinan, Shandong, China
  • 5 Shandong Mental Health Center, Shandong University, Shandong, China

The final, formatted version of the article will be published soon.

    Mild cognitive impairment (MCI) is a condition that impairs activities of daily living, and often transforms to dementia. Repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS) show promise in improving cognitive functions in MCI patients. In this meta-analysis, we aimed to compare the effects of rTMS and tDCS on memory functions in MCI patients. We explored eight databases from their inception to March 16, 2024. We obtained 11 studies with 406 patients with MCI. We used the standardized mean difference (SMD) with a 95% confidence interval (CI) to synthesize the effect size. rTMS and tDCS significantly improved memory functions in MCI patients (SMD = 0.61; 95% CI: 0.41-0.82; P < 0.00001; I 2 = 22%). In subgroup analysis of number of stimulation sessions, both rTMS and tDCS over 10 sessions (SMD = 0.84; 95% CI: 0.50 -1.17, P < 0.00001, I 2 = 0%) significantly improved the memory function in MCI patients. The subgroup analyses on different stimulation types (SMD = 0.78; 95% CI: 0.51-1.06; P < 0.00001; I 2 = 0%) and treatment persistent effects (SMD = 0.93; 95% CI: 0.51-1.35, P < 0.0001, I 2 = 0%) showed that rTMS was more effective than tDCS. rTMS with a stimulation frequency of 10 Hz (SMD = 0.86; 95% CI: 0.51-1.21; P < 0.00001; I 2 = 0%) and over 10 sessions (SMD = 0.98; 95% CI: 0.58-1.38; P < 0.00001; I 2 = 0%) at multiple sites (SMD = 0.97; 95% CI: 0.44-1.49; P = 0.0003; I 2 = 0%) showed a great improvement in the memory performance of patients with MCI. rTMS was more likely to appear temporary side effects (risk ratio (RR) = 3.18, 95% CI: 1.29-7.83, P = 0.01). This meta-analysis suggests that rTMS and tDCS are safe and efficient tools to improve memory functions in patients with MCI, while rTMS had a larger effect than tDCS. rTMS with a stimulation frequency of 10 Hz targeted on multiple sites over 10 sessions showed the greatest effect. We could not conclude parameters of tDCS because of insufficient data.

    Keywords: Mild Cognitive Impairment, Memory, repetitive transcranial magnetic stimulation, transcranial direct current stimulation, Cognitive Function, non-invasive brain stimulation

    Received: 24 May 2024; Accepted: 26 Jul 2024.

    Copyright: © 2024 Hu, Nitsche, Lv, Han, Lin and Qi. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

    * Correspondence:
    Michael A. Nitsche, Department of Psychology and Neurosciences, Leibniz Research Centre for Working Environment and Human Factors, Dortmund, Germany
    Yanxin Lv, Sports Coaching College, Beijing Sports University, Beijing, 100084, China
    Hairong Han, Blood purification Department, The Eighth People’s Hospital of Jinan, Shandong, China
    Xu Lin, Shandong Mental Health Center, Shandong University, Shandong, China
    Fengxue Qi, Sports Coaching College, Beijing Sports University, Beijing, 100084, China

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