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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    • "Transcranial direct current stimulation (tDCS) is a noninvasive brain stimulation technique that induces polarity-dependent alterations of cortical excitability (Nitsche and Paulus, 2000; Nitsche et al., 2003, 2007, 2008). Modulation of dlPFC functions with tDCS has been shown to reduce craving for smoking (Fregni et al., 2008a), marijuana (Boggio et al., 2010), and food in healthy subjects (Fregni et al., 2008b). We thus hypothesized that tDCS over the dlPFC might be a promising therapeutic approach to treat drug dependence. "
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    ABSTRACT: transcranial Direct Current Stimulation (tDCS) over the dorsolateral prefrontal cortex (dlPFC) has been shown to be clinically useful in the treatment of drug addiction. We conducted a double-blind randomized clinical trial aiming to assess the effects of bilateral dlPFC tDCS (left cathodal/right anodal) on crack-cocaine addiction. We defined craving as the primary outcome, and other clinical measurements, including depressive and anxiety symtoms, and quality of life, as secondary outcomes. 17 male crack-cocaine users (mean age 30.4 ± 9.8 SD) were randomized to receive five sessions of active tDCS (2 mA, 35 cm(2), for 20 minutes), every other day, and 19 males (mean age 30.3 ± 8.4 SD) to receive sham-tDCS (placebo), as control group. Craving scores were significantly reduced in the tDCS group after treatment when compared to sham-tDCS (p = 0.028) and to baseline values (p = 0.003), and decreased linearly over four weeks (before, during and after treatment) in the tDCS group only (p = 0.047). Changes of anxiety scores towards increase in the sham-tDCS and decrease in the tDCS group (p = 0.03), and of the overall perception of quality of life (p = 0.031) and of health (p = 0.048) towards decrease in the sham-tDCS group and increase in the tDCS group, differed significantly between groups. Repetitive bilateral tDCS over the dlPFC reduced craving to crack-cocaine use, decreased anxiety and improved quality of life. We hypothesize that tDCS effects may be associated with increased pre-frontal processing and regulation of craving behavior. © The Author 2015. Published by Oxford University Press on behalf of CINP.
    The International Journal of Neuropsychopharmacology 06/2015; DOI:10.1093/ijnp/pyv066 · 4.01 Impact Factor
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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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