Effects of transcranial direct current stimulation (tDCS) on breathing variability and post-exercise hypotension in resistant hypertensive subjects

Abstract

Resistant hypertension (RH) is a complex and multifactorial disease and has been associated with sympathetic nervous system hyperactivity (SNS) and reduction of vagal activity. Increasing the complexity of understanding their pathophysiological mechanisms, recent studies have demonstrated relationships between the autonomic and immune systems. Invasive therapies, as well as physical exercise protocols, have been developed for the treatment of RH; however, hyperactivity of the SNS still remains a challenge for the blood pressure (BP) control. Thus, the use of cerebral stimulation techniques, such as non-invasive transcranial direct current stimulation (tDCS) on the cerebral cortex of RH subjects seems promising due to potential modulation of BP levels. Previous studies have shown that cortical sympathetic modulation by tDCS may reduce blood pressure levels, improve autonomic function and exercise capacity; however, the main outcomes were associated with improved psychic depression in non-RH patients, as well as with the performance of athletes. Thus, the current randomized clinical trial aims to evaluate in RH patients: 1) the presence of periodic breathing and breathing variability during exercise, as well as to test the effects of tDCS on these variables; 2) the effects of tDCS on aerobic post-exercise hypotension; 3) the effects of 10 sessions (2 weeks) of tDCS, controlled by placebo-sham, on hemodynamic, autonomic, inflammatory and ventilatory variables (during the ergospirometry). We hypothesized that tDCS may positively modulate cardiorespiratory responses during an exercise test and potentiate hypotensive effects of exercise, possibly mediated by autonomic, biochemical and inflammatory changes. (AU)