Modulation of risk-taking in marijuana users by transcranial direct current stimulation (tDCS) of the dorsolateral prefrontal cortex (DLPFC)

Cognitive Neuroscience Laboratory and Developmental Disorders Program, Center for Health and Biological Sciences, Mackenzie Presbyterian University, Rua Piaui, 181, 10 Andar, Sao Paulo, SP 01241-001, Brazil.
Drug and alcohol dependence (Impact Factor: 3.42). 12/2010; 112(3):220-5. DOI: 10.1016/j.drugalcdep.2010.06.019
Source: PubMed


Cognitive deficits that are reported in heavy marijuana users (attention, memory, affect perception, decision-making) appear to be completely reversible after a prolonged abstinence period of about 28 days. However, it remains unclear whether the reversibility of these cognitive deficits indicates that (1) chronic marijuana use is not associated with long-lasting changes in cortical networks or (2) that such changes occur but the brain adapts to and compensates for the drug-induced changes. Therefore, we examined whether chronic marijuana smokers would demonstrate a differential pattern of response in comparison to healthy volunteers on a decision-making paradigm (Risk Task) while undergoing sham or active transcranial direct current stimulation (tDCS) of the dorsolateral prefrontal cortex (DLPFC). Twenty-five chronic marijuana users who were abstinent for at least 24h were randomly assigned to receive left anodal/right cathodal tDCS of DLPFC (n=8), right anodal/left cathodal tDCS of DLPFC (n=9), or sham stimulation (n=8); results on Risk Task during sham/active tDCS were compared to healthy volunteers from a previously published dataset. Chronic marijuana users demonstrated more conservative (i.e. less risky) decision-making during sham stimulation. While right anodal stimulation of the DLPFC enhanced conservative decision-making in healthy volunteers, both right anodal and left anodal DLPFC stimulation increased the propensity for risk-taking in marijuana users. These findings reveal alterations in the decision-making neural networks among chronic marijuana users. Finally, we also assessed the effects of tDCS on marijuana craving and observed that right anodal/left cathodal tDCS of DLPFC is significantly associated with a diminished craving for marijuana.

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Available from: Alvaro Pascual-Leone, Dec 19, 2013
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    • "Additionally, several studies have shown that tDCS of the DLPFC can reduce the craving for different types of substance, including alcohol, nicotine, drugs, and food (Boggio et al., 2009a, 2008; Fregni et al., 2008a). Other studies have observed a decrease in risk-taking in healthy volunteers compared with marijuana users (Boggio et al., 2010), a reduction in appetite for risk during ambiguous decisionmaking and a decrease in risk-taking in a risk task (Fecteau et al., 2007a, 2007b) during right anodal/left cathodal stimulation of the right DLPFC. However, the effect of tDCS on the IFG has not previously been reported. "
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    • "In this context, the use of a simple but effective, relatively focal and non-invasive modulator of neuroplasticity – transcranial direct current stimulation (tDCS) – can be tested as an agent to change the addictive behaviour via modulation of dlPFC excitability. Modulation of dlPFC functions with tDCS has been shown to reduce cravings for tobacco (Fregni et al., 2008a), marijuana (Boggio et al., 2010) and food in healthy subjects (Fregni et al., 2008b). For alcohol craving, positive preliminary tDCS data are available. "
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    ABSTRACT: Preliminary small studies have shown that transcranial direct current stimulation (tDCS) reduces craving in alcoholic subjects. It is unclear whether tDCS also leads to changes in clinically meaningful outcomes for alcohol dependence in a properly powered phase II randomized clinical trial. We aimed to investigate whether repetitive tDCS changes the risk of alcohol use relapse in severe alcoholics from outpatient services. Thirty-five subjects were randomized to receive active bilateral [left cathodal/right anodal over the dorsolateral prefrontal cortex (dlPFC)] repetitive (five consecutive days) tDCS (2 mA, 35 cm2, two times daily stimulation for 13 min with a 20-min interval) or sham-tDCS. There were two dropouts before treatment. From 33 alcoholic subjects, 17 (mean age 45.5 ± 8.9 s.d., 16 males) were randomized to sham and 16 (44 ± 7.8 s.d., 16 males) to real tDCS treatment. By the end of the six months of follow-up, two subjects treated with sham (11.8%) and eight treated with real tDCS (50%) were still alcohol-abstinent [p = 0.02, Long-rank (Mantel-Cox) Test, HR = 0.35 (95% CI, 0.14-0.85)]. No differences with regard to changes on scores of craving, frontal function, global mental status, depressive or anxiety symptoms were observed between groups. However, subjects from the tDCS group improved with regard to their overall perception of quality of life (p = 0.02), and increased their scores in the environment domain (p = 0.04) after treatment. Bilateral tDCS over dlPFC reduces relapse probability in severe alcoholic subjects and results in improved perception of quality of life.
    The International Journal of Neuropsychopharmacology 07/2014; 17(11):1-11. DOI:10.1017/S1461145714000984 · 4.01 Impact Factor
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    • "It has also been proposed that non-invasive brain-stimulation treatment effects of addiction are linked to shifts in decision making related to the role of the DLPFC in impulsivity control (e.g. Boggio et al., 2010b; for review, see Fecteau et al., 2010). However, as our study did not assess craving and the effects of the specific electrode setting used in our study have never been explored for the potential to modify craving, testing this hypothesis is not within the scope of this study. "
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    ABSTRACT: Previous results point towards a lateralization of dorsolateral prefrontal cortex (DLPFC) function in risky decision making. While the right hemisphere seems involved in inhibitory cognitive control of affective impulses, the left DLPFC is crucial in the deliberative processing of information relevant for the decision. However, a lack of empirical evidence precludes definitive conclusions. The aim of our study was to determine whether anodal transcranial direct current stimulation (tDCS) over the right DLPFC with cathodal tDCS over the lDLPFC (anodal right/cathodal left) or vice versa (anodal left/cathodal right) differentially modulates risk-taking in a task [the Columbia Card Task (CCT)] specifically engaging affect-charged (Hot CCT) vs. deliberative (Cold CCT) decision making. The facilitating effect of the anodal stimulation on neuronal activity was emphasized by the use of a small anode and a big cathode. To investigate the role of individual differences in risk-taking, participants were either smokers or non-smokers. Anodal left/cathodal right stimulation decreased risk-taking in the 'cold' cognition version of the task, in both groups, probably by modulating deliberative processing. In the 'hot' version, anodal right/cathodal left stimulation led to opposite effects in smokers and non-smokers, which might be explained by the engagement of the same inhibitory control mechanism: in smokers, improved controllability of risk-seeking impulsivity led to more conservative decisions, while inhibition of risk-aversion in non-smokers resulted in riskier choices. These results provide evidence for a hemispheric asymmetry and personality-dependent tDCS effects in risky decision making, and may be important for clinical research on addiction and depression.
    European Journal of Neuroscience 10/2013; 38(12). DOI:10.1111/ejn.12375 · 3.18 Impact Factor
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