Transcranial direct current stimulation (tDCS) of frontal cortex decreases performance on the WAIS-IV intelligence test.
Transcranial direct current stimulation (tDCS) modulates excitability of motor cortex. However, there is conflicting evidence about the efficacy of this non-invasive brain stimulation modality to modulate performance on cognitive tasks. Previous work has tested the effect of tDCS on specific facets of cognition and executive processing. However, no randomized, double-blind, sham-controlled study has looked at the effects of tDCS on a comprehensive battery of cognitive processes. The objective of this study was to test if tDCS had an effect on performance on a comprehensive assay of cognitive processes, a standardized intelligence quotient (IQ) test. The study consisted of two substudies and followed a double-blind, between-subjects, sham-controlled design. In total, 41 healthy adult participants were included in the final analysis. These participants completed the Wechsler Adult Intelligence Scale, Fourth Edition (WAIS-IV) as a baseline measure. At least one week later, participants in substudy 1 received either bilateral tDCS (anodes over both F4 and F3, cathode over Cz, 2 mA at each anode for 20 min) or active sham tDCS (2 mA for 40 s), and participants in substudy 2 received either right or left tDCS (anode over either F4 or F3, cathode over Cz, 2 mA for 20 min). In both studies, the WAIS-IV was immediately administered following stimulation to assess for performance differences induced by bilateral and unilateral tDCS. Compared to sham stimulation, right, left, and bilateral tDCS reduced improvement between sessions on Full Scale IQ and the Perceptual Reasoning Index. This demonstration that frontal tDCS selectively degraded improvement on specific metrics of the WAIS-IV raises important questions about the often proposed role of tDCS in cognitive enhancement.
Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill NC 27599; Neurobiology Curriculum, University of North Carolina at Chapel Hill, Chapel Hill NC 27599.
Kristin K
KK
Sellers
Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill NC 27599.
Juliann M
JM
Mellin
Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill NC 27599.
Caroline M
CM
Lustenberger
Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill NC 27599; Department of Biomedical Engineering, University of North Carolina at Chapel Hill, Chapel Hill NC 27599.
Michael R
MR
Boyle
Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York NY 10029.
Won Hee
WH
Lee
Department of Psychiatry and Behavioral Sciences, Duke University, Durham NC 27710; Department of Biomedical Engineering, Duke University, Durham NC 27710; Department of Electrical and Computer Engineering, Duke University, Durham NC 27710.
Angel V
AV
Peterchev
Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill NC 27599; Neurobiology Curriculum, University of North Carolina at Chapel Hill, Chapel Hill NC 27599; Department of Biomedical Engineering, University of North Carolina at Chapel Hill, Chapel Hill NC 27599; Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill NC 27599; Department of Neurology, University of North Carolina at Chapel Hill, Chapel Hill NC 27599; Neuroscience Center, University of North Carolina at Chapel Hill, Chapel Hill NC 27599. Electronic address: flavio_frohlich@med.unc.edu.
Flavio
F
Fröhlich
D000328:Adult; D005260:Female; D006801:Humans; D007360:Intelligence / Q000502:physiology*; D008297:Male; D010465:Perception / Q000502:physiology*; D011214:Practice, Psychological; D017397:Prefrontal Cortex / Q000502:physiology*; D013850:Thinking / Q000502:physiology*; D065908:Transcranial Direct Current Stimulation / Q000009:adverse effects*; D014888:Wechsler Scales; D055815:Young Adult
Brain stimulation; IQ; Intelligence; Perceptual reasoning; WAIS-IV; tDCS