Modulation of risky choices in recently abstinent dependent cocaine users: a transcranial direct-current stimulation study.

Alessandra Gorini,Gabriella Pravettoni,Claudio Lucchiari,William Russell-Edu

doi:10.3389/fnhum.2014.00661

Alessandra Gorini, Gabriella Pravettoni + Show 2 more

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https://doi.org/10.3389/fnhum.2014.00661

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Abstract

Previous neurobiological and neuropsychological investigations have shown that risk-taking behaviors and addictions share many structural and functional aspects. In particular, both are characterized by an irresistible need to obtain immediate rewards and by specific alterations in brain circuits responsible for such behaviors. In this study, we used transcranial direct-current stimulation over the dorsolateral prefrontal cortex (DLPFC) of two samples of subjects (18 dependent cocaine users and 18 control subjects) to investigate the effects of left and right cortical excitability on two risk tasks: (1) the balloon analog risk task (BART) and (2) the game of dice task (GDT). All subjects randomly received a left anodal/right cathodal stimulation (LAn+), a right anodal/left cathodal stimulation (RAn+), and a sham (placebo) stimulation each run at least 48 h apart. Participants were asked to perform the BART and the GDT immediately before and after each stimulation. Our results reveal that the activation of the DLPFC (left and right) results in a reduction of risky behaviors at the BART task both in controls subjects and cocaine dependent users. The effect of tDCS on GDT, instead, is more complex. Cocaine users increased safe behavior after right DLPFC anodal stimulation, while risk-taking behavior increased after left DLPFC anodal stimulation. Control subjects’ performance was only affected by the anodal stimulation of the right DLPFC, resulting in an increase of safe bets. These results support the hypothesis that excessive risk propensity in dependent cocaine users might be due to a hypoactivation of the right DLPFC and an unbalance interhemispheric interaction. In conclusion, since risky decision-making seems to be, at least in part, responsible for maintenance and relapse of addiction, we argue that a neuromodulation-based approach could represent a valuable adjunct in the clinical treatment of addiction.

Highlights

Drug addiction can be described as a persistent state characterized by loss of control over drug-seeking and the compulsive desire to use drugs for acute rewards regardless of whether they involve risk of aversive consequences (Hyman and Malenka, 2001)
MATERIALS AND METHODS We conducted a single-blind, sham-controlled study to investigate the effect of transcranial direct-current stimulation (tDCS) over the left and right dorsolateral prefrontal cortex (DLPFC) on two decisionmaking tasks in dependent cocaine users compared to control subjects
SUBJECTS Thirty dependent cocaine users diagnosed according to the DSMIV criteria for substance abuse, were recruited in a private hospital in the north of Italy, where they were hospitalized for a period of 4– 6 weeks in order to withdraw from drugs

Summary

Introduction

Drug addiction can be described as a persistent state characterized by loss of control over drug-seeking and the compulsive desire to use drugs for acute rewards regardless of whether they involve risk of aversive consequences (Hyman and Malenka, 2001). Neurobiological studies on addiction have shown an association between the rewarding and reinforcing effects of drugs and the activation of several areas in the mesocorticolimbic network, as well as an altered dopaminergic activity in frontal cortical areas including the dorsolateral prefrontal cortex (DLPFC), the orbitofrontal cortex (OFC), and the anterior cingulate cortex (ACC) (Di Chiara and Imperato, 1988; Carlezon and Wise, 1996; Wise, 1996; Breiter et al, 1997; Kauer and Malenka, 2007; Kalivas and O’Brien, 2008) caused by acute or chronic exposure to addictive drugs. From a neuropsychological point of view, dysfunctions within these frontal and prefrontal cortical circuits cause impulsivity and abnormalities in decision-making, risk perception, cognitive evaluation of consequences and errors, and goal identification that are supposed to play a key role in compulsive drug-seeking behavior (Lubman et al, 2004; Fishbein et al, 2005; Garavan and Stout, 2005; Krain et al, 2006). Several studies have shown significant behavioral impairments of risky decision-making tasks, such as the Iowa gambling task (IGT) and the balloon analog risk task (BART), in substance-dependent individuals [e.g., Wang et al (2013); Balconi et al (2014); Canavan et al (2014); Hulka et al (2014); Yan et al (2014)]

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