Direct-Current Stimulation Does Little to Improve the Outcome of Working Memory Training in Older Adults

• Published in: Psychological science Vol. 28; no. 7; pp. 907 - 920
• Main Authors: Nilsson, Jonna, Lebedev, Alexander V., Rydström, Anders, Lövdén, Martin
• Format: Journal Article
• Language: English
• Published: Los Angeles, CA SAGE Publications 01-07-2017; SAGE PUBLICATIONS, INC
• Subjects: Aged; brain stimulation; Cognition; Cognition & reasoning; Cognition - physiology; Cognitive ability; Cognitive Behavioral Therapy - instrumentation; Cognitive skills training; cognitive training; Cortex; Female; Humans; Learning - physiology; Male; Medicin och hälsovetenskap; Memory; Memory, Short-Term - physiology; Meta-analysis; Neuropsychological Tests; Older people; Prefrontal Cortex - physiology; Short term memory; Stimulation; Systematic review; tDCS; Transcranial direct current stimulation; Transcranial Direct Current Stimulation - methods; Transcutaneous electrical nerve stimulation-TENS; transfer; Transfer, Psychology - physiology; Treatment Outcome; Usefulness; working memory training; brain stimulation; working memory training; transfer; tDCS; cognitive training
• ISSN: 0956-7976; 1467-9280; 1467-9280
• DOI: 10.1177/0956797617698139

The promise of transcranial direct-current stimulation (tDCS) as a modulator of cognition has appealed to researchers, media, and the general public. Researchers have suggested that tDCS may increase effects of cognitive training. In this study of 123 older adults, we examined the interactive effects of 20 sessions of anodal tDCS over the left prefrontal cortex (vs. sham tDCS) and simultaneous working memory training (vs. control training) on change in cognitive abilities. Stimulation did not modulate gains from pre-to posttest on latent factors of either trained or untrained tasks in a statistically significant manner. A supporting meta-analysis (n = 266), including younger as well as older individuals, showed that, when combined with training, tDCS was not much more effective than sham tDCS at changing working memory performance (g = 0.07, 95% confidence interval, or CI = [-0.21, 0.34]) and global cognition performance (g = -0.01, 95% CI = [-0.29, 0.26]) assessed in the absence of stimulation. These results question the general usefulness of current tDCS protocols for enhancing the effects of cognitive training on cognitive ability.