A study found that repetitive transcranial magnetic stimulation (rTMS) to the dorsolateral prefrontal cortex (DLPFC) was safe and may be effective at treating cannabis use disorder (CUD) among patients with schizophrenia. These findings were published in Schizophrenia.

Outpatients (N=19) with schizophrenia who were seeking treatment for CUD were recruited between 2017 and 2020 at the Center for Addiction and Mental Health in Canada. Participants were screened by telephone and eligible patients were assessed for baseline substance-related and psychiatric symptoms following a 12-hour cannabis abstinence period. Patients were randomized to receive active (20-Hz; n=9) or sham (n=10) rTMS to the DLPFC 5 days per week for 28 days. The primary outcomes were self-reported weekly cannabis use, urine toxicology screening, and clinical status as measured by the Positive and Negative Symptom Scale (PANSS) score up to day 56.

The active and sham cohorts were aged mean 34.78±3.45 and 29.10±1.70 years, 9 and 9 of the participants were men, they had 13.56±0.87 and 12.35±0.52 years of education, they were diagnosed with schizophrenia or schizoaffective disorder at 23.89±1.57 at20.40±2.07 years of age, and total Positive and Negative Symptom Scale (PANSS) scores were 54.11±9.69 and 48.60±4.79 points, respectively.

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There were 2 participants who did not complete the experiment, both of whom were assigned to the sham cohort.

Among patients who completed the experiment, grams per day of cannabis decreased by 57.97% among the active and 42.58% among the sham groups (P =.561). From baseline to day 28, time (F[81.67], 4.62; P =.001) was the significant factor for cannabis reduction and neither treatment (F[16.55], 1.98; P =.177) nor the interaction between time and treatment (F[81.67], 1.34; P =.255) were significant.

Similar results were found in urine toxicology screening.

A significant group difference was observed between baseline and day 28 for PANSS total score (P =.02), indicating a reduction in total score among the active cohort.

Active rTMS recipients self-reported a greater reduction in tobacco use with a significant time-by-treatment interaction (F[82.02], 3.15; P =.01).

The active participants reported headache, neck pain, and dizziness and the sham cohort reported headache, tinnitus, electrode site pain, and sinus infection.

This study was limited by its small sample size and should be replicated among a larger independent cohort.

The study authors concluded, “Greater reductions in cannabis use were found in the active versus the sham group; however, these results were not significant. However, the magnitude of standardized change (Cohen’s d-like) between treatment groups indicated medium effects for decreases in self-reported cannabis use (d = 0.72) and Narcochek semi-quantitative urine toxicology (d = 0.55) in the active group compared to the sham group, which are notably in the clinically significant range. Thus, our preliminary findings are promising and in the predicted direction [… and] high-frequency rTMS appears to be well-tolerated.”

Disclosure: Multiple authors declared affiliations with industry. Please refer to the original article for a full list of disclosures.


Bidzinski KK, Lowe DJE, Sanches M, et al. Investigating repetitive transcranial magnetic stimulation on cannabis use and cognition in people with schizophrenia. NPJ Schizophr. 2022;8(1):2. doi:10.1038/s41537-022-00210-6