Spreading Effect of tDCS in Individuals with Attention-Deficit/Hyperactivity Disorder as Shown by Functional Cortical Networks: A Randomized, Double-Blind, Sham-Controlled Trial

Camila Cosmo; Cândida Ferreira; José Garcia Vivas Miranda; Raphael Silva do Rosário; Abrahão Fontes Baptista; Pedro Montoya; Eduardo Pondé de Sena

doi:10.3389/fpsyt.2015.00111

Spreading Effect of tDCS in Individuals with Attention-Deficit/Hyperactivity Disorder as Shown by Functional Cortical Networks: A Randomized, Double-Blind, Sham-Controlled Trial

Front Psychiatry. 2015 Aug 4:6:111. doi: 10.3389/fpsyt.2015.00111. eCollection 2015.

Authors

Camila Cosmo¹, Cândida Ferreira², José Garcia Vivas Miranda², Raphael Silva do Rosário², Abrahão Fontes Baptista³, Pedro Montoya⁴, Eduardo Pondé de Sena⁵

Affiliations

¹ Postgraduate Program, Interactive Process of Organs and Systems, Federal University of Bahia , Salvador , Brazil ; Neuromodulation Center, Spaulding Rehabilitation Hospital, Harvard Medical School , Boston, MA , USA ; Bahia State Department of Health (SESAB) , Salvador , Brazil ; Functional Electrostimulation Laboratory, Biomorphology Department, Federal University of Bahia , Salvador , Brazil.
² Institute of Physics, Federal University of Bahia , Salvador , Brazil.
³ Functional Electrostimulation Laboratory, Biomorphology Department, Federal University of Bahia , Salvador , Brazil ; Postgraduate Program in Medicine and Human Health, School of Medicine, Federal University of Bahia , Salvador , Brazil.
⁴ Research Institute in Health Sciences (IUNICS-IdisPa), University of the Balearic Islands , Palma , Spain.
⁵ Postgraduate Program, Interactive Process of Organs and Systems, Federal University of Bahia , Salvador , Brazil.

Abstract

Background: Transcranial direct current stimulation (tDCS) is known to modulate spontaneous neural network excitability. The cognitive improvement observed in previous trials raises the potential of this technique as a possible therapeutic tool for use in attention-deficit/hyperactivity disorder (ADHD) population. However, to explore the potential of this technique as a treatment approach, the functional parameters of brain connectivity and the extent of its effects need to be more fully investigated.

Objective: The aim of this study was to investigate a functional cortical network (FCN) model based on electroencephalographic activity for studying the dynamic patterns of brain connectivity modulated by tDCS and the distribution of its effects in individuals with ADHD.

Methods: Sixty ADHD patients participated in a parallel, randomized, double-blind, sham-controlled trial. Individuals underwent a single session of sham or anodal tDCS at 1 mA of current intensity over the left dorsolateral prefrontal cortex for 20 min. The acute effects of stimulation on brain connectivity were assessed using the FCN model based on electroencephalography activity.

Results: Comparing the weighted node degree within groups prior to and following the intervention, a statistically significant difference was found in the electrodes located on the target and correlated areas in the active group (p < 0.05), while no statistically significant results were found in the sham group (p ≥ 0.05; paired-sample Wilcoxon signed-rank test).

Conclusion: Anodal tDCS increased functional brain connectivity in individuals with ADHD compared to data recorded in the baseline resting state. In addition, although some studies have suggested that the effects of tDCS are selective, the present findings show that its modulatory activity spreads. Further studies need to be performed to investigate the dynamic patterns and physiological mechanisms underlying the modulatory effects of tDCS.

Trial registration: ClinicalTrials.gov NCT01968512.

Keywords: attention-deficit/hyperactivity disorder; dorsolateral prefrontal cortex; functional cortical networks; spreading effect; transcranial direct current stimulation.

Associated data

ClinicalTrials.gov/NCT01968512