Blinding is compromised for transcranial direct current stimulation at 1 mA for 20 min in young healthy adults

Zsolt Turi; Gábor Csifcsák; Nya Mehnwolo Boayue; Per Aslaksen; Andrea Antal; Walter Paulus; Josephine Groot; Guy E. Hawkins; Birte Forstmann; Alexander Opitz; Axel Thielscher; Matthias Mittner

doi:10.1111/ejn.14403

Blinding is compromised for transcranial direct current stimulation at 1 mA for 20 min in young healthy adults

Zsolt Turi, Gábor Csifcsák, Nya Mehnwolo Boayue, Per Aslaksen, Andrea Antal, Walter Paulus, Josephine Groot, Guy E. Hawkins, Birte Forstmann, Alexander Opitz, Axel Thielscher, Matthias Mittner

Biomedical Engineering

Research output: Contribution to journal › Article › peer-review

60 Scopus citations

Abstract

Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation method that is frequently used to study cortical excitability changes and their impact on cognitive functions in humans. While most stimulators are capable of operating in double-blind mode, the amount of discomfort experienced during tDCS may break blinding. Therefore, specifically designed sham stimulation protocols are being used. The “fade-in, short-stimulation, fade-out” (FSF) protocol has been used in hundreds of studies and is commonly believed to be indistinguishable from real stimulation applied at 1 mA for 20 min. We analysed subjective reports of 192 volunteers, who either received real tDCS (n = 96) or FSF tDCS (n = 96). Participants reported more discomfort for real tDCS and correctly guessed the condition above chance-level. These findings indicate that FSF does not ensure complete blinding and that better active sham protocols are needed.

Original language	English (US)
Pages (from-to)	3261-3268
Number of pages	8
Journal	European Journal of Neuroscience
Volume	50
Issue number	8
DOIs	https://doi.org/10.1111/ejn.14403
State	Published - Oct 1 2019

Bibliographical note

Funding Information:
The writing of this paper was supported by the Research Program, University Medical Center, University of Goettingen awarded to ZT. AT received support from Lundbeckfonden (R118-A11308) and Novo Nordisk Fonden by a synergy grant on Biophysically adjusted state-informed cortex stimulation (BASICS; NNF14OC0011413). This work was supported by the Northern Norway Regional Health Authority (grant no. PFP1237-15) for GC and MM.

Publisher Copyright:
© 2019 Federation of European Neuroscience Societies and John Wiley & Sons Ltd

Keywords

active sham tDCS
blinding
double-blinding
placebo
transcranial direct current stimulation

Publisher link

10.1111/ejn.14403

https://backend.orbit.dtu.dk/ws/files/171275773/Turi_et_al_2019_European_Journal_of_Neuroscience.pdf

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title = "Blinding is compromised for transcranial direct current stimulation at 1 mA for 20 min in young healthy adults",

abstract = "Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation method that is frequently used to study cortical excitability changes and their impact on cognitive functions in humans. While most stimulators are capable of operating in double-blind mode, the amount of discomfort experienced during tDCS may break blinding. Therefore, specifically designed sham stimulation protocols are being used. The “fade-in, short-stimulation, fade-out” (FSF) protocol has been used in hundreds of studies and is commonly believed to be indistinguishable from real stimulation applied at 1 mA for 20 min. We analysed subjective reports of 192 volunteers, who either received real tDCS (n = 96) or FSF tDCS (n = 96). Participants reported more discomfort for real tDCS and correctly guessed the condition above chance-level. These findings indicate that FSF does not ensure complete blinding and that better active sham protocols are needed.",

keywords = "active sham tDCS, blinding, double-blinding, placebo, transcranial direct current stimulation",

author = "Zsolt Turi and G{\'a}bor Csifcs{\'a}k and Boayue, {Nya Mehnwolo} and Per Aslaksen and Andrea Antal and Walter Paulus and Josephine Groot and Hawkins, {Guy E.} and Birte Forstmann and Alexander Opitz and Axel Thielscher and Matthias Mittner",

note = "Funding Information: The writing of this paper was supported by the Research Program, University Medical Center, University of Goettingen awarded to ZT. AT received support from Lundbeckfonden (R118-A11308) and Novo Nordisk Fonden by a synergy grant on Biophysically adjusted state-informed cortex stimulation (BASICS; NNF14OC0011413). This work was supported by the Northern Norway Regional Health Authority (grant no. PFP1237-15) for GC and MM. Publisher Copyright: {\textcopyright} 2019 Federation of European Neuroscience Societies and John Wiley & Sons Ltd",

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AU - Csifcsák, Gábor

AU - Boayue, Nya Mehnwolo

AU - Aslaksen, Per

AU - Antal, Andrea

AU - Paulus, Walter

AU - Groot, Josephine

AU - Hawkins, Guy E.

AU - Forstmann, Birte

AU - Opitz, Alexander

AU - Thielscher, Axel

AU - Mittner, Matthias

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PY - 2019/10/1

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N2 - Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation method that is frequently used to study cortical excitability changes and their impact on cognitive functions in humans. While most stimulators are capable of operating in double-blind mode, the amount of discomfort experienced during tDCS may break blinding. Therefore, specifically designed sham stimulation protocols are being used. The “fade-in, short-stimulation, fade-out” (FSF) protocol has been used in hundreds of studies and is commonly believed to be indistinguishable from real stimulation applied at 1 mA for 20 min. We analysed subjective reports of 192 volunteers, who either received real tDCS (n = 96) or FSF tDCS (n = 96). Participants reported more discomfort for real tDCS and correctly guessed the condition above chance-level. These findings indicate that FSF does not ensure complete blinding and that better active sham protocols are needed.

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