Transcranial direct current stimulation has been shown to modulate the perception of craving in drug abusers by modulating cortical excitability in the posterior-lateral prefrontal region. Regarding the mechanism of craving in methamphetamine users, our aim in this study was to investigate the effectiveness of transcranial direct current stimulation on the posterior-lateral area of the prefrontal cortex in order to change the perception of craving in abstinent methamphetamine addicts. In this cross-over, double-blind, placebo-controlled (sham) study, 32 abstinent right-handed male methamphetamine addicts were included in the study. We randomly applied an andal stimulation and a 20-minute sham stimulation with an intensity of 2 mA on the posterior-lateral area of the right prefrontal cortex of the brain of the subjects, and after 10 minutes of the stimulation, the subjects performed the computerized craving induction test. They used signs. People’s momentary desire to consume before stimulation, simultaneously with stimulation (after 10 minutes of stimulation) and after completion of electrical stimulation was measured with a visual-linear scale (VAS) of 100 degrees. Anode stimulation of the posterior-lateral region of the right prefrontal cortex significantly changed the perception of craving. Our findings in Andal stimulation compared to sham stimulation showed a significant decrease in the urge to consume at rest and after 10 minutes of stimulation (p=0.016). On the other hand, people reported higher cravings caused by drug use symptoms in real stimulation condition than in fake stimulation condition (p=0.012). Our findings showed a position-dependent effect of electrical brain stimulation, while active stimulation of the prefrontal cortex acutely reduced craving at rest. However, this stimulation increased craving in the face of substance cues. These findings show the importance of the prefrontal cortex of the brain both in valuing signs of use and in the desire to use methamphetamine.

Key words: addiction, cue-induced craving, methamphetamine, non-invasive brain stimulation, transcranial direct current stimulation

Transcranial direct current stimulation (tDCS) has been shown to modulate subjective craving ratings in drug dependents by modification of cortical excitability in dorsolateral prefrontal cortex (DLPFC). Given the mechanism of craving in methamphetamine (meth) users, we aimed to test whether tDCS of DLPFC could also alter self-reported craving in abstinent meth users while being exposed to meth cues. In this double-blinded, crossover, sham-controlled study, thirty two right-handed abstinent male meth users were recruited. We applied 20 min ‘anodal’ tDCS (2 mA) or ‘sham’ tDCS over right DLPFC in a random sequence while subjects performed a computerized cue-induced craving task (CICT) starting after 10 min of stimulation. Immediate craving was assessed before the stimulation, after 10 min of tDCS, and after tDCS termination by visual analog scale (VAS) of 0 to 100. Anodal tDCS of rDLPFC altered craving ratings significantly. We found a significant reduction of craving at rest in real tDCS relative to the sham condition (p=0.016) after 10 min of stimulation. On the other hand, cue-induced VAS craving was rated significantly higher in the real condition in comparison with sham stimulation (p=0.012). Our findings showed a state dependent effect of tDCS: while active prefrontal tDCS acutely reduced craving at rest in the abstinent meth users, it increased craving during meth-related cue exposure. These findings reflect the important role of the prefrontal cortex in both cue saliency evaluation and urge to meth consumption.