Transcranial direct current stimulation (tDCS) may reduce the expired CO concentration among opioid users who smoke cigarettes: a randomized sham-controlled study

Transcranial direct current stimulation (tDCS) could be a potential treatment for nicotine dependency. Little is known with regards to the efficacy of this treatment in cigarette-smoking patients with heroin dependency. In this sham-controlled study, we probed the effect of 5-day, 20-min, 2-mA-intensity tDCS treatment on the outcomes of cigarette-smoking. Our objectives are to examine the effects of tDCS on two outcomes: objective expired CO concentration and subjective self-reported number of cigarettes smoked per day. A total of 30 patients were randomized into active or sham control groups. The stimulation site was randomized to anodal stimulation of the left dorsal lateral prefrontal cortex or the orbital frontal cortex. The expired CO concentration was recorded. The patients also reported their cigarette consumption and level of craving prior to each 5-day treatment period and after 5 days of follow-up. tDCS was found to be effective in terms of reducing the expired CO concentration, and both groups demonstrated reduced numbers of cigarettes smoked. However, no significant group difference was found with regards to craving tendency. tDCS may affect objective outcomes related to cigarette-smoking among patients with heroin dependence.