Transcranial direct current stimulation of the frontal-parietal-temporal brain areas reduces cigarette consumption in abstinent heroin users

Transcranial direct current stimulation (tDCS) has been demonstrated to modulate neural activity and related brain functions. In clinical studies, tDCS has been shown to reduce craving in various substance use disorders including cocaine, heroin and nicotine. Our previous report suggested that cathodal tDCS on the frontal-parietal-temporal (FPT) brain areas reduced cigarette consumption in moderate smokers. However, whether it is effective in smokers with history of drug use is unknown. This study investigated the effects of bilateral FPT areas cathodal tDCS on smokers with history of heroin use. 22 abstinent heroin users were recruited and randomly assigned to sham group and tDCS group. The sham group received 30 s tDCS treatment and tDCS group received normal tDCS (one trial of 20 min, 1 mA, cathodal electrodes were placed bilaterally on the FPT areas). The average of daily cigarettes consumption was recorded for the week before the tDCS and the following day after tDCS. In addition, pupil light reflex was measured right before and after tDCS treatment. One trial of tDCS stimulation significantly reduced daily cigarette consumption in smokers who had heroin use history. This reducing effect was also observed in heavy smokers. In addition, this effect on cigarette consumption lasted at least 48 h after the stimulation. Furthermore, it has been shown that opiates decrease pupillary size in humans, we found detectable changes of the dynamic pupil light reflex after bilateral tDCS stimulation. These findings suggest that FPT cathodal tDCS may be an effective approach to reduce cigarette craving in heroin users.