Autonomic Reactivity to Acute Mental Stress Differs Between Women and Men with Post Traumatic Stress Disorder (PTSD)

Abstract

Over 7 million Americans are affected by post‐traumatic stress disorder (PTSD), a debilitating mental illness that is associated with significant cardiovascular disease risk. Women are twice as likely as men to develop PTSD after a traumatic event. A prior study from our laboratory showed that sympathetic nervous system reactivity during combat related and non‐combat related stress is heightened in PTSD; however, this study was conducted in a predominantly male cohort and did not consider the potential influence of sex on neural cardiovascular function in PTSD. The aim of the current study was to determine if women with PTSD have heightened blood pressure (BP), heart rate (HR), and sympathetic reactivity to acute mental stress than men with PTSD. We recruited 15 women and 18 men clinically diagnosed with PTSD and confirmed using the Clinician Administered PTSD Scale (CAPS) and PTSD Checklist‐Military (PCL‐M) surveys. We measured muscle sympathetic nerve activity (MSNA), continuous BP, HR and heart rate variability (HRV) at baseline and during 3 minutes of mental arithmetic. Women and men were matched for race, age (41±2 vs 38±2 years, p=0.191), body mass index (31±2 vs 29±2 kg/m2, p=0.368), CAPS (71 ±9 vs 74 ±4, p=0.732) and PCLM (57 ±5 vs 68 ±4, p=0.129) scores. Likewise, baseline systolic BP (131±5 vs 128±4 mmHg), diastolic BP (76±4 vs 74±2 mmHg) and HR (70±3 vs 64±2 beats/min) were comparable (P>0.05) between women and men. Although resting HRV measures were not different between groups (p>0.05), resting MSNA was higher (p=0.008) in women compared to men (27±3 vs 16±3 bursts/min). In response to mental arithmetic, systolic BP reactivity was higher in women compared to men (Δ+5.1±1 versus Δ+2.2±1 mm Hg, p<0.001). Diastolic BP (p=0.366) and HR (p=0.170) responses were not different. However, MSNA reactivity was higher (p=0.04) in women compared to men (Δ15.2±5 versus Δ6.4±3 bursts/min), suggesting an exaggerated sympathetic response to acute stress. Although RMSSD reactivity was similar between both groups (p=0.347), HF response to mental stress was blunted (p=0.05) in women compared to men, suggesting a greater withdrawal of parasympathetic control of the heart during acute stress. In summary, women with PTSD show an exaggerated blood pressure and sympathetic response to acute mental stress coupled with a blunted parasympathetic control of the heart. These results provide important insight into the physiological mechanisms linking the high risk of PTSD in women and the associated cardiovascular disease and hypertension risk.Support or Funding InformationThis work was supported by National Institutes of Health (NIH) Grant R01 HL135183; NIH R61 AT010457, VA Merit I01CX001065, the Department of Veterans Affairs, Veterans Health Administration, Office of Research and Development, Decatur, Georgia, and the APS STRIDE Undergraduate Summer Research Fellowship, grant program number NHLBI; 1 R25 HL115473‐01.