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. 2021 Jan 5:14:562360.
doi: 10.3389/fnhum.2020.562360. eCollection 2020.

Neurofeedback of Alpha Activity on Memory in Healthy Participants: A Systematic Review and Meta-Analysis

Wen-Hsiu Yeh  1 , Jen-Jui Hsueh  2 , Fu-Zen Shaw  1   2   3
Affiliations

Neurofeedback of Alpha Activity on Memory in Healthy Participants: A Systematic Review and Meta-Analysis

Wen-Hsiu Yeh et al. Front Hum Neurosci. .

Abstract

Background: Neurofeedback training (NFT) has recently been proposed as a valuable technique for cognitive enhancement and psychiatric amelioration. However, effect of NFT of alpha activity on memory is controversial. The current study analyzed previous works in terms of randomized and blinded analyses, training paradigms, and participant characteristics to validate the efficacy of alpha NFT on memory in a healthy population. Objectives: A systematic meta-analysis of studies with randomized controlled trials was performed to explore the effect of alpha NFT on working memory (WM) and episodic memory (EM) in a healthy population. Methods: We searched PubMed, Embase, and Cochrane Library from January 1, 1999, to November 30, 2019. Previous studies were evaluated with the Cochrane risk of bias (RoB). A meta-analysis calculating absolute weighted standardized mean difference (SMD) using random-effects models was employed. Heterogeneity was estimated using I 2 statistics. Funnel plots and Egger's test were performed to evaluate the quality of evidence. Results: Sixteen studies with 217 healthy participants in the control group and 210 participants in the alpha group met the eligibility criteria. Alpha NFT studies with WM measures presented little publication bias (P = 0.116), and 5 of 7 domains in the Cochrane RoB exhibited a low risk of bias. The overall effect size from 14 WM studies was 0.56 (95% CI 0.31-0.81, P < 0.0001; I 2 = 28%). Six EM studies exhibited an effect size of 0.77 (95% CI 0.06-1.49, P = 0.03; I 2 = 77%). Conclusion: Meta-analysis results suggest that alpha NFT seems to have a positive effect on the WM and EM of healthy participants. Future efforts should focus on the neurophysiological mechanisms of alpha NFT in memory.

Keywords: alpha; cognition; memory; neurofeedback; randomized controlled trial.

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Conflict of interest statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Figures

Figure 1
Figure 1
The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) flow diagram presenting the literature searches and the included studies.
Figure 2
Figure 2
Cochran risk of bias tool. Each risk of bias item for each included study and presented as percentages across all included studies.
Figure 3
Figure 3
Funnel plot and Egger's test for meta-analysis of effects of alpha neurofeedback training (NFT) on working memory. Each point represents an independent study for the indicated associate. Coef, coefficient; MSE, mean standard error; SE, standard error; SMD, standardized mean difference; Std_eff, standard effects.
Figure 4
Figure 4
Forest plots for meta-analysis of alpha NFT on working memory in healthy participants. SD, standard deviation; Std, standardized.
Figure 5
Figure 5
Forest plots for meta-analysis of alpha NFT on episodic memory in healthy participants. SD, standard deviation; Std, standardized.
See this image and copyright information in PMC

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