Adrenergic hyperactivity: a missing link between multiple sclerosis and cardiovascular comorbidities?

The aim of the study is to investigate differences in non-standard adrenergic baroreflex sensitivity (BRS) indices in patients with different phenotypes of multiple sclerosis (pwMS) and healthy controls (HC). Retrospective analysis of types of systolic blood pressure (BP) curves during Valsalva maneuver (VM) [balanced (BAR), augmented (AAR) and suppressed (SAR) autonomic responses] and adrenergic baroreflex sensitivity (BRSa) measured with BRSa₁, α-BRSa and β-BRSa in patients with clinically isolated syndrome (CIS), relapsing remitting multiple sclerosis (RRMS), progressive multiple sclerosis (PMS) and HC. We also investigated correlations between BRSa_1, α-BRSa, β-BRSa and resting catecholamine levels. pwMS had higher α-BRSa compared to HC (p = 0.02). There was no difference in BRSa₁, s and β-BRSa between patients with CIS, RRMS and PMS. There was no association between pwMS and HC, and the type of sBP curve [χ2 = 4.332, p = 0.114]. pwMS and BAR or AAR had higher supine systolic and diastolic BP compared to pwMS and SAR. There was a significant correlation between α-BRSa and upright systolic BP (r_p =0.194, p = 0.017), α-BRSa and norepinephrine (r_s =0.228, p = 0.021), and BRSa₁ and epinephrine (r_s = 0.226, p = 0.040). pwMS and HC exhibit different alpha-adrenergic response to Valsalva maneuver. These results may explain the connection between MS and increased cardiovascular risk.