A meta-analysis of non-invasive brain stimulation and autonomic functioning: implications for brain-heart pathways to cardiovascular disease

Given the intrinsic connection between the brain and the heart, a recent body of research emerged with the aim to influence cardiovascular system functioning by non-invasive brain stimulation (NIBS) methods such as repetitive transcranial magnetic stimulation and transcranial direct current stimulation. Despite the implications of cardiovascular activity modulation for therapeutic purposes, such effects of NIBS have not yet been quantified. The aim of this study was to meta-analyze studies on NIBS effects on blood pressure (BP), heart rate (HR) and its variability (HRV). PubMed and Scopus databases were searched for English language studies conducted in humans. Twenty-nine studies were eligible for the analyses. Pooled effect sizes (Hedges' g) were compared. Random effect models were used. NIBS was effective in reducing HR (g=0.17) and enhancing HRV (g=0.30). A marginal effect emerged for BP (g=0.21). Significant moderators were the stimulation technique and the site of stimulation. Results show that NIBS affects cardiovascular and autonomic nervous system activity, confirming a potential pathogenic brain-heart pathway to cardiovascular disease.