Effects of transcranial direct current stimulation on Nicotine Use Disorder: A systematic review and meta-analysis

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 behaviours in Nicotine Use Disorder (NUD) and explore neuroimaging findings related to these effects.

Systematic review following PRISMA 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 behaviours were reviewed. GRADE methodology was applied to assess evidence quality.

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 behaviours with neuroimaging support namely fMRI, fNIRS and EEG, providing additional insights to neurobiology of nicotine addiction.

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.