Spontaneous baroreflex control of sympathetic nerve activity and heart rate in young adults with major depressive disorder

Abstract

Blunted cardiac baroreflex sensitivity is evident in middle-aged adults with depression in remission and likely contributes to increased cardiovascular disease morbidity and mortality. In young adults with major depressive disorder (MDD), there is some evidence that sympathetic outflow at rest is elevated and graded in relation to depressive symptom severity; however, few studies have examined arterial baroreflex function in young adults with MDD. Here, we tested the hypotheses that spontaneous baroreflex control of muscle sympathetic nerve activity (MSNA) and heart rate (HR) would both be attenuated in young adults with symptomatic MDD (unmedicated) compared to healthy non-depressed adults (HA). Nine HA (22±3 yrs; 6 female) and 10 adults with symptomatic MDD of moderate severity [21±5 yrs; 8 female; 15±3 on the Patient Health Questionnaire-9 (possible score range: 0-27)] participated. MSNA (peroneal microneurography), HR (electrocardiogram), and beat-to-beat blood pressure (BP; finger photoplethysmography) were continuously measured during 10 min of supine rest. To determine spontaneous sympathetic baroreflex gain, weighted linear regression analyses between spontaneous changes in MSNA and diastolic BP (3 mmHg bins) were performed. To estimate spontaneous cardiac baroreflex gain, the relation between systolic BP and R-R interval was determined using the sequence technique. At rest, there were no group differences in MSNA burst incidence (28±10 HA vs. 21±10 bursts/100 heartbeats MDD; p=0.19), HR (62±9 HA vs. 69±11 bpm MDD; p=0.13), or mean arterial pressure (81±6 HA vs. 82±5 mmHg MDD; p=0.70). Sympathetic baroreflex gain was not different between HA and MDD (-3.4±0.8 HA vs. -3.0±1.5 bursts/100 heartbeats/mmHg MDD; p=0.53). There were also no differences in overall cardiac baroreflex gain between groups (24±11 HA vs. 19±6 ms/mmHg MDD; p=0.24). Likewise, there were no group differences in cardiac baroreflex gain when derived separately during either BP rises or BP falls (both p>0.05). These preliminary data demonstrate that spontaneous baroreflex control of both MSNA and HR are preserved in young adults with symptomatic MDD, suggesting that impairments in baroreflex function in adults with depression may only manifest later in the disease trajectory. NIH R21MH123928 and R00 HL133414 This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.