Effect of transcranial direct current stimulation and transcranial magnetic stimulation on the cognitive function of individuals with Alzheimer’s disease: a systematic review with meta-analysis and meta-regression

ABSTRACT

Objective

To analyze the effects of transcranial direct current stimulation (tDCS) and transcranial magnetic stimulation (TMS) on the cognitive function of individuals with Alzheimer’s disease (AD).

Methods

This systematic review with meta-analysis and meta-regression included randomized clinical trials published until 05/2022. We included studies conducted with individuals with AD of both sexes, aged between 55 and 85 years, treated with tDCS, TMS, or both.

Results

Twenty-one studies were included in the systematic review and sixteen in the meta-analysis. Meta-regression suggested a significant influence of anodic tDCS with current intensity of 1.5 mA on cognitive function. Significant results were found with treatment frequencies of three and five days a week for two weeks. Subgroup analysis found that anodic tDCS influences cognitive function, regardless of AD stage. Similar was observed for TMS using a frequency of 20 Hz and current intensity of 90% of the resting motor threshold.

Discussion

Anodal tDCS and 20 Hz TMS have demonstrated the ability to improve cognitive function in AD by modulating neural activity. These therapies are safe and well-tolerated, offering promise as adjuncts to available pharmacological treatments. Studies with greater methodological rigor and parameter standardization are warranted. Comprehensive investigations involving neuroimaging techniques may provide a better understanding of the interaction between induced electrical fields and the complex neural networks affected in AD, paving the way for more personalized and effective neurostimulation approaches

KEYWORDS:

• Alzheimer’s disease
• transcranial direct current stimulation
• transcranial magnetic stimulation
• electrical stimulation
• cognition

Disclosure statement

The authors declare that the research was conducted without any commercial or financial relationships that could be construed as a potential conflict of interest.

Author contributions

CCM and SA: study conception and design; KVC, ICS, CCM, and CBM: data collection and analysis; SM, CCM, LC, SS, MQ ans LPC: writing or critically revising the manuscript or both. All authors contributed and approved the submitted version.

Data availability statement

The data supporting the conclusions of this article will be made available by the authors without reservation.

Additional information

Funding

The author(s) reported there is no funding associated with the work featured in this article.