Sex differences in brain excitability revealed by concurrent iTBS/fNIRS
Rebecca L.D. Kan, Bella B.B. Zhang, Tim T.Z. Lin, Alvin Tang, Adam W.L. Xia, Penny Ping Qin, Minxia Jin, Tommy Kwan Hin Fong, Benjamin Becker, Suk‐Yu Yau, Georg S. Kranz
Abstract
Sex differences have been claimed an imperative factor in the optimization of psychiatric treatments. Intermittent theta-burst stimulation (iTBS), a patterned form of repetitive transcranial magnetic stimulation, is a promising non-invasive treatment option. Here, we investigated whether the real-time neural response to iTBS differs between men and women, and which mechanisms may mediate these differences. To this end, we capitalized on a concurrent iTBS/functional near-infrared spectroscopy setup over the left dorsolateral prefrontal cortex, a common clinical target, to test our assumptions. In a series of experiments, we show (1) a biological sex difference in absolute hemoglobin concentrations in the left dorsolateral prefrontal cortex in healthy participants; (2) that this sex difference is amplified by iTBS but not by cognitive tasks; and (3) that the sex difference amplified by iTBS is modulated by stimulation intensity. These results inform future stimulation treatment optimizations towards precision psychiatry.