Cognitive Enhancement of Repetitive Transcranial Magnetic Stimulation in Patients With Mild Cognitive Impairment and Early Alzheimer’s Disease: A Systematic Review and Meta-Analysis

Abstract

Repetitive transcranial magnetic stimulation (rTMS), a non-invasive brain stimulation technique, has been considered as a potentially effective treatment for the cognitive impairment in patients with mild cognitive impairment (MCI) and Alzheimer’s Disease (AD). However, the effectiveness of this therapy is still under debate due to the variety of rTMS parameters and individual differences including distinctive stages of AD in the previous studies. The current meta-analysis is aiming to assess the cognitive enhancement of rTMS treatment on patients of MCI and early AD. Three datasets (PubMed, Web of Science and CKNI) were searched with relative terms and finally twelve studies with 438 participants (231 in the rTMS group and 207 in the control group) in thirteen randomized, double-blind and controlled trials were included. Random effects analysis revealed that rTMS stimulation significantly introduced cognitive benefits in patients of MCI and early AD compared with the control group (mean effect size, 1.17; 95% CI, 0.76 - 1.57). Most settings of rTMS parameters (frequency, session number, stimulation site number) significantly enhanced global cognitive function, and the results revealed that protocols with 10 Hz repetition frequency and DLPFC as the stimulation site for 20 sessions can already be able to produce cognitive improvement. The cognitive enhancement of rTMS could last for one month after the end of treatment and patients with MCI were likely to benefit more from the rTMS stimulation. Our meta-analysis added important evidence to the cognitive enhancement of rTMS in patients with MCI and early AD and discussed potential underlying mechanisms about the effect induced by rTMS.

Effects of rTMS treatment on global cognitive function in Alzheimer's disease: A systematic review and meta-analysis

“…In addition, our subgroup analysis of number of treatment sessions showed that long-term treatment (≥20 sessions) may have resulted in better cognitive improvement in patients with AD. Our findings agree with those of Lin et al ( 2019 ), Jiang et al ( 2020 ), Wang et al ( 2020 ), and Xie et al ( 2021 ).…”

“…Previous meta-analyses have reported significant effects (Sitzer et al, 2006 ; Cheng et al, 2018 ; Xie et al, 2021 ) and no effects (Lin et al, 2019 ; Chu et al, 2021 ) of combined CT with rTMS. In our study, the combination of rTMS and CT did not result in additional improvement.…”

Therapeutic approaches for improving cognitive function in the aging brain

“…In recent years, rTMS has been considered as a promising intervention for cognitive improvement ( Iriarte and George, 2018 ). Two systematic reviews reported high frequency rTMS might show a moderate effect on cognition in AD and MCI patients ( Cheng et al, 2018 ; Xie et al, 2021 ). However, the conclusion was limited by the small sample size of included studies.…”

Mechanisms of abnormal adult hippocampal neurogenesis in Alzheimer’s disease

“…The clinical manifestations of AD patients are characterized by comprehensive dementia, such as memory impairment, aphasia, loss of use, loss of recognition, impairment of visuospatial skills, executive dysfunction, and personality and behavioral changes. Mild cognitive impairment is the precursor stage of dementia, characterized by subjective cognitive deficits and objective memory impairment in daily life ( Xie et al, 2021 ). Patients have difficulties in reasoning, abstract concepts, and even language difficulties.…”