Key pointsr Patients with post-traumatic stress disorder (PTSD) are at a significantly higher risk of developing hypertension and cardiovascular disease. The mechanisms underlying this increased risk are not known.r Studies have suggested that PTSD patients have an overactive sympathetic nervous system (SNS) that could contribute to cardiovascular risk; however, sympathetic function has not previously been rigorously evaluated in PTSD patients.r Using direct measurements of sympathetic nerve activity and pharmacological manipulation of blood pressure, we show that veterans with PTSD have augmented SNS and haemodynamic reactivity during both combat-related and non-combat related mental stress, impaired sympathetic and cardiovagal baroreflex sensitivity, and increased inflammation.r Identifying the mechanisms contributing to increased cardiovascular (CV) risk in PTSD will pave the way for developing interventions to improve sympathetic function and reduce CV risk in these patients.Abstract Post-traumatic stress disorder (PTSD) is associated with increased cardiovascular (CV) risk. We tested the hypothesis that PTSD patients have augmented sympathetic nervous system (SNS) and haemodynamic reactivity during mental stress, as well as impaired arterial baroreflex sensitivity (BRS). Fourteen otherwise healthy Veterans with combat-related PTSD were compared with 14 matched Controls without PTSD. Muscle sympathetic nerve activity (MSNA), continuous blood pressure (BP) and electrocardiography were measured at baseline, as well as during two types of mental stress: combat-related mental stress using virtual reality combat exposure (VRCE) and non-combat related stress using mental arithmetic (MA). A cold pressor test (CPT) was administered for comparison. BRS was tested using pharmacological manipulation of BP via the Modified Oxford technique at rest and during VRCE. Blood samples were analysed for inflammatory biomarkers. Baseline characteristics, MSNA and haemodynamics were similar between the groups. In PTSD vs. Controls, MSNA (+8.2 ± 1.0 vs. +1.2 ± 1.3 bursts min -1 , P < 0.001) and heart rate responses (+3.2 ± 1.1 vs. −2.3 ± 1.0 beats min -1 , P = 0.003) were significantly augmented during VRCE. Similarly, in PTSD vs. Controls, MSNA (+21.0 ± 2.6 vs. +6.7 ± 1.5 bursts min -1 , P < 0.001) and diastolic BP responses (+6.3 ± 1.0 vs. +3.5 ± 1.0 mmHg, P = 0.011) were significantly augmented during MA but not during CPT (P = not significant). In the PTSD group, sympathetic BRS (-1.2 ± 0.2 vs. -2.0 ± 0.3 burst incidence mmHg and cardiovagal BRS (9.5 ± 1.4 vs. 23.6 ± 4.3 ms mmHg −1 , P = 0.008) were significantly blunted at rest. PTSD patients had significantly higher highly sensitive-C-reactive protein levels compared to Controls (2.1 ± 0.4 vs. 1.0 ± 0.3 mg L −1 , P = 0.047). Augmented SNS and haemodynamic responses to mental stress, blunted BRS and inflammation may contribute to an increased CV risk in PTSD.

Patients with posttraumatic stress disorder (PTSD) have elevated sympathetic nervous system reactivity and impaired sympathetic and cardiovagal baroreflex sensitivity (BRS). Device-guided slow breathing (DGB) has been shown to lower blood pressure (BP) and sympathetic activity in other patient populations. We hypothesized that DGB acutely lowers BP, heart rate (HR), and improves BRS in PTSD. In 23 prehypertensive veterans with PTSD, we measured continuous BP, ECG, and muscle sympathetic nerve activity (MSNA) at rest and during 15 min of DGB at 5 breaths/min ( n = 13) or identical sham device breathing at normal rates of 14 breaths/min (sham; n = 10). Sympathetic and cardiovagal BRS was quantified using pharmacological manipulation of BP via the modified Oxford technique at baseline and during the last 5 min of DGB or sham. There was a significant reduction in systolic BP (by -9 ± 2 mmHg, P < 0.001), diastolic BP (by -3 ± 1 mmHg, P = 0.019), mean arterial pressure (by -4 ± 1 mmHg, P = 0.002), and MSNA burst frequency (by -7.8 ± 2.1 bursts/min, P = 0.004) with DGB but no significant change in HR ( P > 0.05). Within the sham group, there was no significant change in diastolic BP, mean arterial pressure, HR, or MSNA burst frequency, but there was a small but significant decrease in systolic BP ( P = 0.034) and MSNA burst incidence ( P = 0.033). Sympathetic BRS increased significantly in the DGB group (-1.08 ± 0.25 to -2.29 ± 0.24 bursts·100 heart beats·mmHg, P = 0.014) but decreased in the sham group (-1.58 ± 0.34 to -0.82 ± 0.28 bursts·100 heart beats·mmHg, P = 0.025) (time × device, P = 0.001). There was no significant difference in the change in cardiovagal BRS between the groups (time × device, P = 0.496). DGB acutely lowers BP and MSNA and improves sympathetic but not cardiovagal BRS in prehypertensive veterans with PTSD. NEW & NOTEWORTHY Posttraumatic stress disorder is characterized by augmented sympathetic reactivity, impaired baroreflex sensitivity, and an increased risk for developing hypertension and cardiovascular disease. This is the first study to examine the potential beneficial effects of device-guided slow breathing on hemodynamics, sympathetic activity, and arterial baroreflex sensitivity in prehypertensive veterans with posttraumatic stress disorder.

Patients with post‐traumatic stress disorder (PTSD) are at significantly higher risk of developing hypertension and cardiovascular disease. Low‐grade inflammation and overactive sympathetic nervous system (SNS) activity are suggested as contributing mechanisms. Our prior studies showed that while SNS reactivity during stress is heightened in PTSD, resting MSNA and inflammation was not elevated in young combat Veterans with PTSD as a group; however, prior results did not take into account the potential influence of PTSD symptom severity on neural cardiovascular function. The aim of the current study was to determine if PTSD patients with greater PTSD symptoms measured via the gold‐standard clinician administered PTSD scale (CAPS) have higher SNS activity and inflammation compared to PTSD patients with less severe symptoms. To answer this question, we recruited 21 veterans clinically diagnosed with PTSD (mean CAPS score, 68±4). We measured muscle sympathetic nerve activity (MSNA) via microneurography and blood pressure using standard technique. We collected blood samples to measure serum levels of two inflammatory biomarkers: highly sensitive C‐reactive protein (hsCRP) and interleukin‐6 (IL‐6). For data analysis, the participants were grouped based on the median CAPS score of 70, with the low CAPS group (L‐CAPS) having a score ≤ 70 and the high CAPS group (H‐CAPS) having a score > 70. The two groups (L‐CAPS, n=11; H‐CAPS, n=10) were matched for age, body mass index (BMI) and selective serotonin reuptake inhibitor (SSRI) prescription. Resting blood pressure and heart rate were similar between the two groups. However, the H‐CAPS group had a significantly greater MSNA at baseline when quantified as both burst frequency (26±5 vs 13±2 bursts/min, p= 0.011) and burst incidence (35±6 vs 21±3 bursts/100hb, p= 0.022) compared to the L‐CAPS group. Similarly, hsCRP (2.02±0.71 vs 0.74±0.18, p= 0.036) and IL‐6 (5.44±1.86 vs 2.35±0.73, p= 0.055) levels were higher in the H‐CAPS group compared to the L‐CAPS group. Furthermore, the levels of hsCRP (r= 0.766, p< 0.001) and IL‐6 (r= 0.594, p=0.007) were positively correlated with MSNA. When the groups were analyzed separately, the correlation between MSNA and hsCRP was stronger in the H‐CAPS group (r=0.822, p=0.012) than the L‐CAPS group (r=0.604, p=0.065). These results suggest that the severity of PTSD is associated with chronically increased MSNA and inflammation, and SNS overactivity may be mechanistically linked to inflammation in severe PTSD. Support or Funding Information Supported by NIH HL‐098744, NIH DK‐00756, VA Merit I01CX001065, AHA 15CSA24340001 This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.