Transcranial direct current stimulation improves the QT variability index and autonomic cardiac control in healthy subjects older than 60 years

Abstract

Background

Noninvasive brain stimulation technique is an interesting tool to investigate the causal relation between cortical functioning and autonomic nervous system (ANS) responses.

Objective

The objective of this report is to evaluate whether anodal transcranial direct current stimulation (tDCS) over the temporal cortex influences short-period temporal ventricular repolarization dispersion and cardiovascular ANS control in elderly subjects.

Subjects and methods

In 50 healthy subjects (29 subjects younger than 60 years and 21 subjects older than 60 years) matched for gender, short-period RR and systolic blood pressure spectral variability, QT variability index (QTVI), and noninvasive hemodynamic data were obtained during anodal tDCS or sham stimulation.

Results

In the older group, the QTVI, low-frequency (LF) power expressed in normalized units, the ratio between LF and high-frequency (HF) power, and systemic peripheral resistances decreased, whereas HF power expressed in normalized units and α HF power increased during the active compared to the sham condition (P<0.05).

Conclusion

In healthy subjects older than 60 years, tDCS elicits cardiovascular and autonomic changes. Particularly, it improves temporal ventricular repolarization dispersion, reduces sinus sympathetic activity and systemic peripheral resistance, and increases vagal sinus activity and baroreflex sensitivity.

Keywords:

• transcranial direct current stimulation
• QT variability
• heart rate variability
• autonomic nervous system
• aging

Acknowledgments

The Italian Ministry of Health Young Researcher Grant (GR-2011-02348232) awarded to Cristina Ottaviani has funded the study. The authors would like to thank Grazia Spitoni and Giorgio Pireddu for their valuable advice on the use of tDCS technique.

Disclosure

The authors report no conflicts of interest in this work.