Heart Rate Variability Moderates the Association Between Trait Anxiety and Sympathetic Nerve Activity in Humans

BACKGROUND: – Chronic anxiety increases the risk of incident hypertension, yet mechanisms remain equivocal. Recent evidence documents that trait anxiety is positively associated with muscle sympathetic nerve activity (MSNA), a known contributor to hypertension risk. The purpose of this study was to address the hypothesis that the association between trait anxiety, MSNA, and elevated blood pressure would be moderated by cardiac vagal activity estimated via heart rate variability (HRV). METHODS: – Resting blood pressure, MSNA (microneurography), and heart rate (ECG) were collected at rest in 130 adults (71 male, 59 female; age, 25±8 years; body mass index, 25±4 kg/m²). Moderation analyses were used to investigate the moderating role of HRV on the association between trait anxiety, MSNA, and blood pressure. RESULTS: – The association between trait anxiety and MSNA was significantly moderated by resting HRV such that the relationship between anxiety and MSNA was stronger (B=0.322, P=0.005) in those with lower HRV (−1 SD) compared with those with average (B=0.146, P=0.067) or higher (+1 SD) HRV (B=−0.031, P=0.785). Conversely, HRV did not moderate the positive association between trait anxiety and blood pressure. CONCLUSIONS: – The present findings demonstrate that elevated trait anxiety is associated with elevated sympathetic neural activity and blood pressure. The association between trait anxiety and elevated sympathetic nerve activity is particularly prominent in those with low HRV, suggesting a potential utility of HRV as a cardiovascular risk biomarker in individuals with heightened anxiety.