Effects of transcranial direct current stimulation on nicotine use disorder: a systematic review and meta-analysis.

INTRODUCTION

Transcranial direct current stimulation (tDCS) is a viable non-invasive approach to counter nicotine addiction. This systematic review and meta-analysis aim to investigate the effects of tDCS on smoking behaviors in nicotine use disorder (NUD) and explore neuroimaging findings related to these effects.

METHODS

Systematic review following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines shortlisted 21 studies. Primary outcome measures were effects of tDCS vs sham on smoking (i) craving, (ii) consumption, and (iii)accompanying neuroimaging results. Random effects meta-analysis was conducted on 6 comparisons for smoking craving and 13 comparisons for smoking consumption. Anodal and cathodal stimulations were evaluated as moderator variables via meta-regression. Five studies with neuroimaging data supporting tDCS effects on smoking behaviors were reviewed. Grading of Recommendations Assessment, Development and Evaluation methodology was applied to assess evidence quality.

RESULTS

Compared to sham, tDCS produced a small reduction in nicotine craving (Hedges' g = -0.26, 95%CI [-0.51, -0.01]) with moderate certainty, and moderate reduction in consumption (Hedges' g = -0.48, 95%CI [-0.79, -0.17]) with low certainty; all within the first day post-stimulation. Moderator analyses did not identify specific electrode placements that effectively reduce nicotine craving or intake. Five studies evaluated tDCS effects on smoking behaviors with neuroimaging support namely functional magnetic resonance imaging, functional near-infrared spectroscopy, and electroencephalography, providing additional insights to neurobiology of nicotine addiction.

CONCLUSION

Current evidence indicates that tDCS may be associated with changes in craving and consumption in NUD. Further research is required to establish efficacy, identify key moderators, and integrate neuroimaging to explore tDCS effects in smoking cessation.

IMPLICATIONS: Our study adds to the current knowledge on the efficacy of tDCS in smoking cessation. It highlights the need for larger studies to further strengthen efficacy, identify key moderators and integrate neuroimaging to elucidate tDCS' mechanisms underlying successful smoking cessation.