Evidence map›Paper›PMID 33098709›Full record

ArticleThe European journal of neuroscience2021

Is the "end-of-study guess" a valid measure of sham blinding during transcranial direct current stimulation?

Christopher Turner, Catherine Jackson, Gemma Learmonth

Open access · hybridAbstract read
PubMed Full text at PMC Publisher
In one paragraph

Article in The European journal of neuroscience, 2021. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 27 papers, 2 of them syntheses that pooled it.

0numbers the graph read from it
0cells of the map it votes in
27citing papers in PubMed, 2 pooled it
2.1field-weighted citation impact, top 12% of its field
1 · What the graph read from it

What it found

Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.

The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.

2 · The registry

The trial behind it

Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.

Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.

3 · Its place in the literature

Who cites it

27 citing papers in PubMed, 2 syntheses or guidelines pooled it, 34 citations in OpenAlex.

  1. Pooled it
  2. Digitalized transcranial electrical stimulation: A consensus statement.Clinical neurophysiology : official journal of the International Federation of Clinical Neurophysiology · 2022
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4 · The record

Corrections and comments

PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.

5 · Who and what money

Authors and funding

3 authors at 2 institutions in 1 country.

Christopher TurnerSchool of Psychology, University of Glasgow, Glasgow, UK.
Catherine JacksonSchool of Psychology, University of Glasgow, Glasgow, UK.
Gemma LearmonthSchool of Psychology, University of Glasgow, Glasgow, UK.ORCID 0000-0003-4061-4464
University of Glasgow · GBWellcome Centre for Human Neuroimaging · GB

Funding

Wellcome Trust 209209/Z/17/Z
6 · The paper itself

Abstract

Studies using transcranial direct current stimulation (tDCS) typically incorporate a fade-in, short-stimulation, fade-out sham (placebo) protocol, which is assumed to be indistinct from a 10-30 min active protocol on the scalp. However, many studies report that participants can dissociate active stimulation from sham, even during low-intensity 1 mA currents. We recently identified differences in the perception of an active (10 min of 1 mA) and a sham (20 s of 1 mA) protocol that lasted for 5 min after the cessation of sham. In the present study we assessed whether delivery of a higher-intensity 2 mA current would exacerbate these differences. Two protocols were delivered to 32 adults in a double-blinded, within-subjects design (active: 10 min of 2 mA, and sham: 20 s of 2 mA), with the anode over the left primary motor cortex and the cathode on the right forehead. Participants were asked "Is the stimulation on?" and "How sure are you?" at 30 s intervals during and after stimulation. The differences between active and sham were more consistent and sustained during 2 mA than during 1 mA. We then quantified how well participants were able to track the presence and absence of stimulation (i.e. their sensitivity) during the experiment using cross-correlations. Current strength was a good classifier of sensitivity during active tDCS, but exhibited only moderate specificity during sham. The accuracy of the end-of-study guess was no better than chance at predicting sensitivity. Our results indicate that the traditional end-of-study guess poorly reflects the sensitivity of participants to stimulation, and may not be a valid method of assessing sham blinding.

Indexed as

Motor CortexTranscranial Direct Current StimulationAdultDouble-Blind MethodElectrodesHumansScalpplaceboprimary motor cortexreaction timeshamtDCS

Identifiers

PMID33098709
PMCPMC8048983
OpenAlexW3094259528

What OpenQuestion holds

Textmetadata
LicenceCC BY
Read underepoch 390

Registered trials

None linked

Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.