Transcranial alternating current stimulation barely enhances working memory in healthy adults: A meta-analysis

Area of Science:

• Neuroscience
• Cognitive Science
• Neuromodulation

Background:

• Working memory (WM) is crucial for cognitive functions.
• Transcranial alternating current stimulation (tACS) aims to modulate brain rhythms to enhance WM.
• Previous meta-analyses suggested positive effects of tACS on WM.

Purpose of the Study:

• To meta-analyze the effects of tACS on working memory performance.
• To investigate potential moderators and publication bias in tACS research on WM.
• To provide an updated assessment of tACS efficacy for WM enhancement.

Main Methods:

• A meta-analysis of 143 tACS effects on WM from 42 studies (2014-2023) involving 1386 healthy adults.
• Calculation of overall effect size (Hedges' g) and analysis of moderators.
• Correction for publication bias to assess true effect sizes.

Main Results:

• The overall effect size for tACS intended to improve WM was negligible (Hedges' g = 0.076) and dropped to zero after correcting for publication bias.
• Interventions using antiphase tACS to disrupt brain synchronization reliably decreased WM performance (Hedges' g = -0.266).
• Targeted frequency band was the only significant moderator; recent studies predominantly reported null effects.

Conclusions:

• Current tACS protocols demonstrate minimal to no enhancement of working memory in healthy adults.
• Disruptive tACS protocols negatively impact WM performance.
• Further research is required to develop effective tACS methods for WM improvement.