One left dorsolateral prefrontal cortical HF-rTMS session attenuates HPA-system sensitivity to critical feedback in healthy females.

OBJECTIVE Although left dorsolateral prefrontal cortical (DLPFC) repetitive Transcranial Magnetic Stimulation (rTMS) is used to treat major depression, its underlying neurophysiological working mechanism remains to be determined. Prior research suggested that the clinical effects could be mediated by affecting the hypothalamic-pituitary-adrenal (HPA) system, but experimental studies in healthy individuals did not yield clear results. However, in healthy individuals, the influence of HF-rTMS on the HPA-system may only be detected when it is challenged. METHODS In 30 rTMS naïve healthy females we evaluated the effect of one sham-controlled high frequency (HF)-rTMS session applied to the left DLPFC on the stress hormone cortisol by collecting salivary cortisol samples. In order to increase stress levels, 5min after stimulation, all participants performed the Critical Feedback Task (CFT), during which they were criticized on their performance. To take possible mood influences into account, all participants were also assessed with Visual Analogue Scales (VAS). RESULTS The experimental procedure did not affect mood differently in the real or sham stimulation. Area under the curve (AUCi) analysis showed that one real HF-rTMS session significantly influenced HPA-system sensitivity, as demonstrated by a decrease in cortisol concentrations. The sham procedure yielded no effects. CONCLUSIONS In line with former observations in major depression, one real left DLPFC HF-rTMS session significantly influenced HPA-system sensitivity in experimentally stressed females, resulting in decreases in cortisol levels.