Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
Review
. 2021 Mar 29:17:971-990.
doi: 10.2147/NDT.S259499. eCollection 2021.

A Systematic Review and Meta-Analysis of Transcranial Direct Current Stimulation to Remediate Age-Related Cognitive Decline in Healthy Older Adults

Aprinda Indahlastari  1   2 , Cheshire Hardcastle  1   2 , Alejandro Albizu  1   3 , Stacey Alvarez-Alvarado  1   2 , Emanuel M Boutzoukas  1   2 , Nicole D Evangelista  1   2 , Hanna K Hausman  1   2 , Jessica Kraft  1   3 , Kailey Langer  1   2 , Adam J Woods  1   2   3
Affiliations
Review

A Systematic Review and Meta-Analysis of Transcranial Direct Current Stimulation to Remediate Age-Related Cognitive Decline in Healthy Older Adults

Aprinda Indahlastari et al. Neuropsychiatr Dis Treat. .

Abstract

Background: Transcranial direct current stimulation (tDCS) has been proposed as a possible method for remediating age-associated cognitive decline in the older adult population. While tDCS has shown potential for improving cognitive functions in healthy older adults, stimulation outcomes on various cognitive domains have been mixed.

Methods: A systematic search was performed in four databases: PubMed, EMBASE, Web of Science, and PsychInfo. Search results were then screened for eligibility based on inclusion/exclusion criteria to only include studies where tDCS was applied to improve cognition in healthy older adults 65 years and above. Eligible studies were reviewed and demographic characteristics, tDCS dose parameters, study procedures, and cognitive outcomes were extracted. Reported effect sizes for active compared to sham group in representative cognitive domain were converted to Hedges' g.

Main results: A total of thirteen studies involving healthy older adults (n=532, mean age=71.2+5.3 years) were included in the meta-analysis. The majority of included studies (94%) targeted the prefrontal cortex with stimulation intensity 1-2 mA using various electrode placements with anodes near the frontal region. Across all studies, we found Hedges' g values ranged from -0.31 to 1.85 as reported group effect sizes of active stimulation compared to sham.

Conclusion: While observed outcomes varied, overall findings indicated promising effects of tDCS to remediate cognitive aging and thus deserves further exploration. Future characterization of inter-individual variability in tDCS dose response and applications in larger cohorts are warranted to further validate benefits of tDCS for cognition in healthy older adults.

Keywords: aging; cognitive decline; tDCS; tES.

PubMed Disclaimer

Conflict of interest statement

The authors report no conflicts of interest in this work.

Figures

Figure 1
Figure 1
PRISMA diagram illustrates search results for each stage of the systematic review process. Notes: Adapted from  Moher D, Liberati A., Tetzlaff J, Altman DG. Preferred reporting items for systematic reviews and meta-analyses: The PRISMA statement.PLoS Medicine. 2009;6(7):e1000097. Creative Commons license and disclaimer available from: http://creativecommons.org/licenses/by/4.0/legalcode
Figure 2
Figure 2
Summary of quality assessment using the Cochrane Risk Bias Tool. (A) Risk of bias graph showing overall risks across thirteen studies. (B) Risk of bias ratings for individual studies.
Figure 3
Figure 3
Forest plot and bubble plot to illustrate weighted effect sizes in all studies. (A) Forest plot categorized by each cognitive domain illustrates computed Hedges’ g across cognitive domains. (B) Bubble plot demonstrates significant meta-regression result of age vs effect size (Hedges’ g), and the location of two identified outliers (Nilsson et al, 2017 and Manenti et al, 201759). Individual weights assigned to each study is indicated by the diameter of the circle. The estimated slope of this curve shows the significant effect (R2=0.3828, p=0.006) of mean study age on treatment effects (Hedges’ g).
Figure 4
Figure 4
Funnel plots to assess publication bias. (A) Egger’s test for asymmetry (k=17) indicates publication bias exists in our sample (t[16]=2.86, p=0.0119). (B) Duval and Tweedie trim and fill procedure (k=22) to correct biases shows significant results (Hedges’ g=0.489, CI=[0.259; 0.719], t[21]=4.42, p=0.0002). Different color shades illustrate different p-values: p>0.5 (white), p<0.05 (dark blue), p<0.025 (blue), p<0.01 (light blue).
See this image and copyright information in PMC

References

    1. Ortman JM, Velkoff VA, Hogan H. An aging nation: the older population in the United States. Econ Stat Adm US Dep Commer. 2014;1964:1–28. doi:10.1016/j.jaging.2004.02.002 - DOI
    1. Sofi F, Valecchi D, Bacci D, et al. Physical activity and risk of cognitive decline: a meta-analysis of prospective studies. J Intern Med. 2011;269(1):107–117. doi:10.1111/j.1365-2796.2010.02281.x - DOI - PubMed
    1. Colcombe S, Kramer AF. Fitness effects on the cognitive function of older adults: a meta-analytic study. Psychol Sci. 2003;14(2):125–130. doi:10.1111/1467-9280.t01-1-01430 - DOI - PubMed
    1. Bherer L, Peterson MS, Kramer AF, Colcombe S, Erickson K, Becic E. Training effects on dual-task performance: are there age-related differences in plasticity of attentional control? Psychol Aging. 2005;20(4):695–709. doi:10.1037/0882-7974.20.4.695 - DOI - PubMed
    1. Erickson KI, Miller DL, Roecklein K. The Aging Hippocampus: interactions between Exercise, Depression, and BDNF. Neurosci. 2012;18(1):82–97. doi:10.1177/1073858410397054 - DOI - PMC - PubMed

LinkOut - more resources