Multi-session anodal transcranial direct current stimulation enhances lower extremity functional performance in healthy older adults
Authors: Shapour Jaberzadeh
Enayatollah Bakhshi
Dawson Kidgell
Mohamad Rostami
Fatemeh Ehsani
Sepideh Ansari
Mohammad Reza Nourbakhsh
Zahra Mosallanezhad
Journal: Experimental brain research (2020)
Discipline: NEUROSCIENCE & BEHAVIOR
Keywords: Balance; Gait; Lower extremity functional performance; Older adults; Transcranial direct current stimulation.
Affiliations: Department of Physiotherapy, Research Center on Aging, University of Social Welfare and Rehabilitation Sciences, Tehran, 1985713831, Iran., Department of Physiotherapy, Research Center on Aging, University of Social Welfare and Rehabilitation Sciences, Tehran, 1985713831, Iran. ., Speech Therapy Department, Musculoskeletal Rehabilitation Research Center, Ahvaz Jundishapur University of Medical Science, Ahvaz, Iran., Neuromuscular Rehabilitation Research Centre, Semnan University of Medical Science, Semnan, Iran., Department of Physiotherapy, School of Primary Health Care, Faculty of Medicine, Nursing and Health Sciences, Monash University, Melbourne, Australia., Department of Physical Therapy, University of North Georgia, Dahlonega, GA, USA., Department of Biostatistics, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran.

Abstract:  The aim of this study was to examine the effects of 5 days of anodal-transcranial direct current stimulation (a-tDCS) over the primary motor cortex (M1) on lower extremity functional performance in healthy elderly people. This was a randomized, double-blinded, sham-controlled study whereby 32 healthy older individuals participated in two groups. The intervention group received 20 min of a-tDCS (1 mA) over the M1 on five consecutive days. The sham group received the same stimulation, but the tDCS device was turned off after 30 s of stimulation. Participants were asked to perform the Timed Up and Go (TUG), 30-s Chair Stand Test (30-s CST), and a Modified Figure of Eight Walk Test (MFEWT) on the first day before tDCS application, immediately, 30 min, and 1 week after the last session of stimulation. Results of the a-tDCS group showed that most of the test values had significant changes in post-test assessments compared to the pre-test (p &lt; 0.05). When comparing the anodal and sham tDCS groups, the results showed a significant improvement in TUG and time-MFEWT immediately after (p = 0.02, p = 0.01), 30 min after (p = 0.04, p = 0.01) and 1 week after the last session of stimulation (p = 0.01, p = 0.01). Improvements in performance of the 30-s CST and the number of steps-MFEWT were not significant, except at 1 week after the last session for the steps-MFEWT (p = 0.04). The application of 20 min a-tDCS over the M1 for 5 consecutive days improves lower extremity functional performance in the healthy older participants. 

Retracted: No

PubPeer comments:
 There seem to be some serious issues here. There are quite a few incorrectly reported p-values. Consider all of the 1.0s in table 3, a few simple calculations reveal that they are all, or nearly all wrong. They are all still greater than .05 but the reported one is too high. But this leads one to wondering which is actually correct, the p-value or the CI? If the p-value is correct the CI is wrong in width, position, or both. Then one questions the tDCS group in the same table and, sure enough, taking the CIs and effects as true leads one to find many errors in the p-values by orders of magnitude (e.g. steps-MFEWT 1-3 should be .01). But, which reported value is incorrect? The p-value is only incorrect assuming all other values are correct. In addition, the largest standardized effect sizes in the whole paper lie in the side effects section. There was no analysis of these but you have many effect sizes between groups clearly well over 1.0 here that exceed those of interest to the researchers. A placebo effect is never discussed and the side effects are only discussed in saying they are mild for most. On average they are, but there are clearly individuals, given the means and SDs, that report some substantial side effects. One might want to see if this side effect correlated with the reported effect, especially given that it s larger. There s also a typo last row of Table 3 sham CI should have -0.52... perhaps? Something is clearly wrong there. ,