Elsevier

Brain Stimulation

Volume 7, Issue 1, January–February 2014, Pages 130-132
Brain Stimulation

Transcranial Direct Current Stimulation (tDCS)/Transcranial Alternating Current Stimulation (tACS)
Short Communication
Bilateral Transcranial Direct Current Stimulation Over Dorsolateral Prefrontal Cortex Changes the Drug-cued Reactivity in the Anterior Cingulate Cortex of Crack-cocaine Addicts

https://doi.org/10.1016/j.brs.2013.09.007Get rights and content

Abstract

Background

Patients addicted to crack-cocaine routinely have difficulty sustaining treatment, which could be related to dysfunctional cerebral activity that occurs in addiction.

Objective

To investigate the indirect electrophysiological effects of single transcranial direct current stimulation (tDCS) on cocaine-addicted brains.

Methods

The patients received either left cathodal/right anodal or sham stimulation over the DLPFC. The region of interest was the anterior cingulate cortex (ACC) during the N2 time window (200–350 ms). Event-related potentials in the ACC were measured during visual presentation of crack-related cues or neutral cues.

Results

Low-resolution brain electromagnetic tomography (LORETA) indicated that exposure to crack-related images led to increased activity in the ACC in the sham group, while the tDCS group showed decreased ACC activity after visualization of drug cues.

Conclusion

Prefrontal tDCS specifically modulated the ACC response during exposure to visual drug cues in crack-cocaine users.

Introduction

It has been suggested that prefrontal dysfunction, particularly dysfunction of cognitive control, may be related to the loss of control over drug use that can lead to addiction [1]. Thus, treatment aiming to improve cognitive control over drug intake is clinically useful. Transcranial direct current stimulation (tDCS) is a noninvasive brain stimulation technique that induces polarity-dependent alterations of cortical excitability [2], [3], [4], [5], [6], [7], [8]. It can modulate the function of deeper cortical areas, such as the anterior cingulate cortex (ACC) [9], [10], [11], [12], which seems to be involved in drug-related attention bias [1]. Considering this evidence, we hypothesize that tDCS over the dorsolateral prefrontal cortex (DLPFC), a prefrontal area primarily involved in cognitive control, will extend its modulation of the ACC in the addicted brain, thereby changing drug-related cue processing. In this study, we examine the N2 component (200–350 ms) of ACC activity during visual presentation of drug-related cues after a single exposure of bilateral (left cathodal/right anodal) tDCS over the DLPFC.

Section snippets

Subjects

Thirteen crack-cocaine addicted subjects, as defined by the DSM-IV, were recruited for this trial. The mean age of the participants was 30 ± 7 (SD) years, and the mean time of drug abstinence was 16 ± 23 (SD) days. Treatment and data collection were conducted according to the Declaration of Helsinki. This report is part of the results from the study registered in the ClinicalTrials.gov Protocol Registration System under identifier NCT01337297.

EEG recording

Electrophysiological recordings were obtained

Results

The sham (n = 6) and tDCS (n = 7) groups were matched regarding socio-demographic characteristics and pattern of drug use (data not shown). Changes in the N2 component of the ACC activity (mean current density ± SD) were recorded during neutral or crack-related cue presentations (Fig. 1). The ACC activity during the N2 segment was similar for neutral images before and after brain stimulation or sham stimulation. However, the ACC activity was increased (P < 0.0001) during exposure to

Discussion

Here, we observe increased ACC activity in the sham group and decreased activity in the tDCS group during visualization of crack-related cues but not neutral cues. Our stimulation protocol involves left cathodal/right anodal stimulation. It is well-established that cathodal tDCS decreases cortical excitability [5], [6], [7], [8]. This could suggest that the left cathode but not the right anode over the (left) DLPFC is related to the reduced activity in the ACC during crack-related image

Acknowledgments

We thank Dr. Janine Moscon for help recruiting patients for this trial.

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    Financial disclosures: CLC received a student scholarship from a governmental institution (CAPES). The authors report no conflicts of interest regarding the content of this manuscript.

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