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

Wada M.; Petersen N.; Wong B.; Kim B.; Kim J.; McRae-Clark A.; Durazzo T.; Sahlem G. · medRxiv : the preprint server for health sciences · 2026

**Background & Methods** This secondary analysis examined data from a randomized, sham-controlled trial investigating whether dorsolateral prefrontal cortex repetitive transcranial magnetic stimulation (DLPFC-rTMS) delivered during cannabis cue exposure affects tobacco consumption among tobacco-using individuals with cannabis use disorder (CUD). Treatment-seeking adults with moderate or severe CUD and baseline tobacco use received either active or sham 10-Hz DLPFC-rTMS over 10 treatment visits (n=20; 10 active, 10 sham), with linear mixed-effects models analyzing weekly percentage changes in tobacco consumption from baseline through treatment and follow-up periods. **Key Findings** - Active DLPFC-rTMS was associated with significantly greater reduction in tobacco consumption compared to 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, and larger reductions in cannabis use did not lead to compensatory increases in tobacco consumption. - The findings suggest possible cross-substance effects of DLPFC-rTMS, indicating that cannabis-targeted neuromodulation may produce beneficial effects on concurrent tobacco use without triggering substance substitution patterns. **Dosage & Administration** 10-Hz DLPFC-rTMS delivered during cannabis cue exposure over 10 treatment visits. Specific pulse parameters, intensity (% motor threshold), train duration, and inter-train intervals were not detailed in the abstract. **Safety & Adverse Effects** Not reported. **Evidence Quality** This is a small, preliminary secondary analysis (n=20) from a parent RCT examining an exploratory outcome, limiting generalizability and statistical power. The short-term follow-up (1-week post-treatment) is insufficient to establish durability of effects, and longer-term outcomes are unknown. The study design does not allow definitive causal inference regarding cross-substance mechanisms. Publication on medRxiv indicates this is a preprint not yet peer-reviewed. The authors acknowledge these limitations and explicitly call for larger trials specifically designed to investigate cannabis-tobacco co-use. Evidence is best classified as preliminary/exploratory, requiring confirmation in adequately powered, prospectively designed studies.

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