For many people living with major depressive disorder, one important question remains unanswered before starting treatment: can alcohol, nicotine, or cannabis use reduce the effectiveness of transcranial magnetic stimulation? New research published in the Journal of Affective Disorders provides reassuring evidence that low to moderate substance use may not substantially interfere with TMS depression treatment, challenging assumptions that have influenced clinical decision making for years.
The findings contribute to the growing body of advances in interventional psychiatry by helping clinicians better understand which patient characteristics truly influence treatment outcomes and which may deserve further investigation before becoming barriers to care.
Why Substance Use Has Been A Clinical Concern
Substance use frequently occurs alongside major depressive disorder. Alcohol, nicotine, and cannabis are among the most commonly used substances in this population, and previous research has shown that substance use disorders can worsen psychiatric symptoms and complicate recovery.
Because TMS works by modulating activity in brain circuits involved in mood regulation, researchers have questioned whether substances that affect brain plasticity and cortical function might also reduce the antidepressant benefits of treatment. Expert guidelines have even recommended limiting certain forms of substance use before beginning TMS, despite limited direct evidence supporting those recommendations.
Until now, surprisingly little real world research had evaluated whether everyday patterns of recreational substance use actually influence antidepressant response.
How Researchers Evaluated TMS Depression Treatment
Investigators conducted a retrospective analysis of 356 adults receiving TMS for major depressive disorder at McLean Hospital and affiliated outpatient clinics between 2014 and 2025. Participants completed routine assessments of depressive symptoms before treatment and again after five or six weeks of therapy.
The research team examined several common substance use patterns, including alcohol consumption frequency, typical number of drinks, tobacco use, nicotine vaping, cannabis use, and cannabis vaping. These factors were compared with changes in Patient Health Questionnaire 9 scores, a widely used measure of depression severity.
Importantly, researchers adjusted for age, sex, and baseline depression severity to better isolate any relationship between substance use and treatment response.
TMS Depression Treatment Showed Consistent Outcomes
The primary finding was straightforward. Most measures of alcohol, nicotine, and cannabis use were not significantly associated with antidepressant improvement following TMS.
Although one subgroup reporting alcohol use two to three times per week appeared to experience greater symptom improvement, the investigators found no consistent dose response relationship. Higher alcohol consumption did not reliably predict either better or worse outcomes, and similar patterns were absent across nicotine and cannabis measures.
The authors concluded that these isolated findings were likely insufficient to establish a meaningful clinical relationship.
Instead, the overall data suggest that low to moderate recreational substance use, as commonly reported in routine clinical practice, may not substantially reduce the effectiveness of TMS for depression.
Understanding Why The Results Matter
The study addresses an important gap between clinical recommendations and real world evidence.
Many existing guidelines encourage reducing or stopping alcohol or cannabis use before beginning TMS because of theoretical concerns regarding brain plasticity and treatment response. While these recommendations remain appropriate when safety concerns or substance use disorders are present, the current findings suggest that recreational use at lower levels may not meaningfully alter antidepressant outcomes.
This distinction matters because TMS already faces significant access barriers, including insurance approvals, treatment schedules, geographic availability, and cost. Adding unnecessary exclusions based on limited evidence could further reduce access for patients who may benefit from therapy.
Strengths And Remaining Questions
One notable strength of the study is its naturalistic design. Rather than examining highly selected clinical trial participants, researchers evaluated patients receiving routine clinical care across multiple treatment protocols, making the findings more representative of everyday psychiatric practice.
However, several important limitations remain.
Most participants reported relatively low levels of substance use, meaning the study cannot determine whether heavy alcohol consumption, cannabis dependence, nicotine dependence, or active substance use disorders influence TMS response differently. The research also relied on self reported substance use rather than biological testing and could not evaluate changes in substance use during treatment.
Future prospective studies using more detailed assessments of substance use patterns, timing, quantity, and dependence severity will help clarify whether specific forms of substance use affect treatment efficacy or safety.
Expanding Access Through Better Evidence
As precision psychiatry continues to evolve, understanding which patient characteristics truly predict treatment success becomes increasingly valuable.
This study suggests that low to moderate recreational alcohol, nicotine, and cannabis use alone should not automatically be viewed as a major predictor of poor antidepressant response to TMS. While additional research remains necessary, the findings provide encouraging evidence that many patients may still benefit from treatment without unnecessary exclusion based solely on modest substance use.
By replacing assumptions with carefully collected clinical data, researchers are helping move interventional psychiatry toward more individualized, evidence based care that balances patient safety with broader access to effective depression treatments.
Citations
- Gonzalez DA, Osama T, Vandekar S, et al. Substance Use and Antidepressant Response to Transcranial Magnetic Stimulation in Major Depressive Disorder. Journal of Affective Disorders. 2026. https://doi.org/10.1016/j.jad.2026.122233
- McClintock SM, Reti IM, Carpenter LL, et al. Consensus Recommendations for the Clinical Application of Repetitive Transcranial Magnetic Stimulation (rTMS) in the Treatment of Depression. Journal of Clinical Psychiatry. 2018;79(1):16cs10905. DOI: 10.4088/JCP.16cs10905. PubMed: https://pubmed.ncbi.nlm.nih.gov/28541649/
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