A Randomized, Double-Blind, Sham-Controlled Trial of Transcranial Direct Current Stimulation in Attention-Deficit/Hyperactivity Disorder.
BACKGROUND
Current standardized treatments for cognitive impairment in attention-deficit/hyperactivity disorder remain limited and their efficacy restricted. Transcranial direct current stimulation (tDCS) is a promising tool for enhancing cognitive performance in several neuropsychiatric disorders. Nevertheless, the effects of tDCS in reducing cognitive impairment in patients with attention-deficit/hyperactivity disorder (ADHD) have not yet been investigated.


METHODS
A parallel, randomized, double-blind, sham-controlled trial was conducted to examine the efficacy of tDCS on the modulation of inhibitory control in adults with ADHD. Thirty patients were randomly allocated to each group and performed a go/no-go task before and after a single session of either anodal stimulation (1 mA) over the left dorsolateral prefrontal cortex or sham stimulation.


RESULTS
A nonparametric two-sample Wilcoxon rank-sum (Mann-Whitney) test revealed no significant differences between the two groups of individuals with ADHD (tDCS vs. sham) in regard to behavioral performance in the go/no go tasks. Furthermore, the effect sizes of group differences after treatment for the primary outcome measures-correct responses, impulsivity and omission errors--were small. No adverse events resulting from stimulation were reported.


CONCLUSIONS
According to these findings, there is no evidence in support of the use of anodal stimulation over the left dorsolateral prefrontal cortex as an approach for improving inhibitory control in ADHD patients. To the best of our knowledge, this is the first clinical study to assess the cognitive effects of tDCS in individuals with ADHD. Further research is needed to assess the clinical efficacy of tDCS in this population.


BACKGROUND
ClinicalTrials.gov NCT01968512.
Postgraduate Program, Interactive Process of Organs and Systems, Federal University of Bahia, Salvador, Bahia, Brazil; Spaulding Neuromodulation Center, Spaulding Rehabilitation Hospital, Harvard Medical School, Boston, Massachusetts, United States of America; Bahia State Health Department (SESAB), Salvador, Bahia, Brazil; Functional Electrostimulation Laboratory, Biomorphology Department, Federal University of Bahia, Salvador, Bahia, Brazil.
Camila
C
Cosmo
Functional Electrostimulation Laboratory, Biomorphology Department, Federal University of Bahia, Salvador, Bahia, Brazil; Postgraduate Program on Medicine and Human Health, School of Medicine, Federal University of Bahia, Salvador, Bahia, Brazil.
Abrahão Fontes
AF
Baptista
Postgraduate Program, Interactive Process of Organs and Systems, Federal University of Bahia, Salvador, Bahia, Brazil.
Arão Nogueira
AN
de Araújo
Institute of Physics, Federal University of Bahia, Salvador, Bahia, Brazil.
Raphael Silva
RS
do Rosário
Institute of Physics, Federal University of Bahia, Salvador, Bahia, Brazil.
José Garcia Vivas
JG
Miranda
Research Institute on Health Sciences (IUNICS-IdisPa), University of the Balearic Islands, Palma, Spain.
Pedro
P
Montoya
Postgraduate Program, Interactive Process of Organs and Systems, Federal University of Bahia, Salvador, Bahia, Brazil.
Eduardo Pondé
EP
de Sena
D000328:Adult; D001289:Attention Deficit Disorder with Hyperactivity / Q000628:therapy*; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017397:Prefrontal Cortex / Q000502:physiology / Q000503:physiopathology; D065908:Transcranial Direct Current Stimulation