Transcranial direct current stimulation modulates autonomic nervous system and reduces ambulatory blood pressure in hypertensives

Abstract

<b>Purpose</b>: Transcranial direct current stimulation (tDCS) seems to positively modulate the autonomic nervous system in different clinical conditions and healthy subjects; however, its effects on hypertensive (HTN) patients are not completely known. This study aimed to evaluate the effects of a tDCS or SHAM session (20 min) on blood pressure (BP) and autonomic variables of HTN patients.<b>Materials and Methods</b>: Subjects (n = 13) were randomly submitted to SHAM and tDCS sessions (1 week of <i>washout</i>). Hemodynamic and autonomic variables were measured at baseline, during, and immediately after tDCS or SHAM stimulation (Finometer®, Beatscope). Ambulatory BP measurement (ABPM) was evaluated after the experimental period.<b>Results</b>: Hemodynamic variables were not changed by tDCS, except for the fall in peripheral vascular resistance (Δ = -1696.51 ± 204.65 dyn.s/cm5). After the tDCS, sympathetic modulation was decreased (-61.47%), and vagal modulation was increased (+38.09%). Such acute autonomic changes may have evoked positive results observed in 24 hs-systolic blood pressure (Δ = -8.4 ± 6.2; <i>P</i> = .0022) and 24hs-diastolic blood pressure (Δ = -5.4 ± 4.2; <i>P</i> = .0010) in tDCS subjects compared with that in SHAM.<b>Conclusion</b>: These findings suggest that the tDCS could promote positive acute adjustments on cardiac autonomic control and reduced values on 24-hs BP of HTN patients. More than a proof-of-concept, these results may point out to the future, where brain stimulation (tDCS) can be used to HTN syndromes, such as refractory HTN.