Sympathetic and blood pressure reactivity in young adults with major depressive disorder

Background: Sympathetic and blood pressure (BP) hyper-reactivity to stress may contribute to increased cardiovascular disease (CVD) risk in adults with major depressive disorder (MDD); however, whether this is evident in young adults with MDD without comorbid disease remains unclear. We hypothesized that acute stress-induced increases in muscle sympathetic nerve activity (MSNA) and BP would be exaggerated in young adults with MDD compared to healthy non-depressed young adults (HA) and that, in adults with MDD, greater symptom severity would be positively related to MSNA and BP reactivity. Methods: In 28 HA (17 female) and 39 young adults with MDD of mild-to-moderate severity (unmedicated; 31 female), MSNA (microneurography) and beat-to-beat BP (finger photoplethysmography) were measured at rest and during the cold pressor test (CPT) and Stroop color word test (SCWT). Results: There were no group differences in resting MSNA (p = 0.24). Neither MSNA nor BP reactivity to either the CPT [MSNA: ∆24 ± 10 HA vs. ∆21 ± 11 bursts/min MDD, p = 0.67; mean arterial pressure (MAP): ∆22 ± 7 HA vs. ∆21 ± 10 mmHg MDD, p = 0.46)] or the SCWT (MSNA: ∆-4 ± 6 HA vs. ∆-5 ± 8 bursts/min MDD, p = 0.99; MAP: ∆7 ± 8 HA vs ∆9 ± 5 mmHg MDD; p = 0.82) were different between groups. In adults with MDD, symptom severity predicted MAP reactivity to the CPT (β = 0.78, SE = 0.26, p = 0.006), but not MSNA (p = 0.42). Limitations: The mild-to-moderate symptom severity reflects only part of the MDD spectrum. Conclusions: Neither sympathetic nor BP stress reactivity are exaggerated in young adults with MDD; however, greater symptom severity may amplify BP reactivity to stress, thereby increasing CVD risk.