Rethinking intensity: Repetitive transcranial magnetic stimulation across ethnic populations

Repetitive transcranial magnetic stimulation (rTMS) targeting the left dorsolateral prefrontal cortex is a widely used adjunctive therapy for various neurological and psychiatric disorders. Traditionally, the standard practice for dosing rTMS has involved adjusting the intensity to a defined percentage of the motor threshold. However, we perceive anatomical differences among ‘ White’ , ‘ Han Chinese ’ and ‘ Black or African American’ ethnic groups that result in unequal doses of stimulation at the left dorsolateral prefrontal cortex, a prime target for therapeutic rTMS. Therefore, we hypothesize that diverse ethnic populations experience different therapeutic effects with FDA-approved rTMS protocols that have been adopted globally. This also raises concerns about varying therapeutic effects and potential biases in existing research comparing efficacy across ethnicities. More importantly, our hypothesis emphasizes the need to tailor rTMS safety guideline for diverse ethnic populations. We call for well-powered clinical trials to systematically examine the effects of rTMS intensity in diverse ethnic groups.