A Preliminary Study of Repetitive Transcranial Magnetic Stimulation for Cannabis Use Disorder and Its Effects on Concurrent Tobacco Use

Objectives: Tobacco and cannabis co-use is common, and reductions in one substance may theoretically lead to compensatory increases in the other. This secondary analysis examined whether cannabis cue-induced dorsolateral prefrontal cortex repetitive transcranial magnetic stimulation (DLPFC-rTMS) affects tobacco consumption among tobacco-using individuals with cannabis use disorder (CUD). Methods: Data were analyzed from a randomized, sham-controlled trial of DLPFC-rTMS for CUD. Participants were treatment-seeking adults with moderate or severe CUD who reported baseline tobacco use. Active or sham 10-Hz DLPFC-rTMS was delivered during cannabis cue exposure over 10 treatment visits. Linear mixed-effects models examined group differences in weekly percentage change from baseline in tobacco consumption over treatment and follow-up, adjusting for baseline tobacco consumption. Additional models examined whether changes in cannabis use were associated with changes in tobacco use. Results: Twenty participants were included, with 10 assigned to active rTMS and 10 to sham. Active rTMS was associated with a greater reduction in tobacco consumption than sham at 1-week post-treatment (t = -2.49, p = 0.015). Changes in cannabis use were not significantly associated with group differences in tobacco reduction. Estimated group differences did not indicate compensatory increases in tobacco use among participants with larger reductions in cannabis use. Conclusions: Cannabis cue-induced DLPFC-rTMS was associated with a short-term reduction in tobacco consumption relative to sham among tobacco-using individuals with CUD. These preliminary findings suggest possible cross-substance effects of DLPFC-rTMS and did not indicate compensatory tobacco increases. Larger trials specifically designed for cannabis-tobacco co-use are warranted.