Impact of tDCS on cerebral autoregulation in aging and in patients with cerebrovascular diseases

Abstract

Following seminal articles on the technique and underlying mechanisms of transcranial direct current stimulation (tDCS) at the turn of this century,1 tDCS has gained special attention in neurorehabilitative research, given its ability to modulate brain function in a polarity-specific manner in stroke patients together with an excellent safety profile.2 However, an important safety concern emerged recently with regard to its impact on cerebral autoregulation, given a report on decreased autoregulation after 15 minutes anodal tDCS (atDCS) over primary motor cortex (M1) in young healthy subjects.3 Cerebral autoregulation, assessed by vasomotor reactivity (VMR), reflects the autonomic ability of cerebral arterioles to dilate following a vasodilatory stimulus. It is consistently decreased in patients with cerebrovascular diseases,4 and has been linked to stroke risk.5 Thus, a decrease of VMR after atDCS may be harmful to patients with already impaired VMR, such as stroke patients.4 Importantly, >40 ongoing trials with stroke patients and atDCS are registered on [www.clinicaltrials.gov][1] as of May 2014. Thus, the concerns raised by Vernieri et al.3 may carry important clinical implications. Acknowledgment: The authors thank Dr. Ulrike Grittner for advice on statistical analysis. [1]: http://www.clinicaltrials.gov