Heart Rate Variability Is Not Associated with Altered Emotional Modulation of Pain or Spinal Nociception.

Abstract

Heart rate variability (HRV) is a physiological measure of beat-to-beat variation in time between heartbeats that reflects competing influences of the sympathetic and parasympathetic branches of the autonomic nervous system (ANS). Research suggests that both ANS branches, and consequently, HRV, are regulated by the central autonomic network (CAN), a widely distributed and interconnected circuit of cortical, limbic, and brainstem areas that modulate ANS activity to meet environmental demands based on current internal physiological conditions. Given its role in modifying internal states, the CAN has been implicated as an important circuit in emotion regulation, and previous researchers have hypothesized that HRV may be a physiological marker related to emotion regulation ability. Indeed, low HRV has been associated with disorders characterized by emotion dysregulation (i.e., depressive and anxiety disorders.) Thus, the current study was conducted to determine whether HRV (calculated using the root mean square of successive differences [RMSSD] and autoregressive high frequency spectral power), divided into tertiles reflecting low, medium, and high levels of HRV, was associated with altered emotional modulation of pain or spinal nociception (assessed from the nociceptive flexion reflex, NFR) during and emotional picture-viewing paradigm known as emotional controls of nociception (ECON). The sample was comprised of 261 healthy, pain-free men and women. It was hypothesized that low HRV would be associated with altered emotional modulation of pain/NFR relative to the other tertile groups for both measures of HRV, with greater facilitation of pain/NFR during negatively valenced pictures and impaired inhibition of pain/NFR during positively valenced pictures. Multilevel modeling analyses revealed that emotional modulation of pain and spinal nociception were not moderated by HRV. Thus, HRV does not appear to promote amplification of pain and nociception via emotional processes, at least not in healthy individuals. These research results were supported by a grant titled, "Native American Pain Disparities: Exploring Nociceptive Processing Differences" (Project Number: 1R01MD007807-01).