Date of Award

2022

Document Type

Open Access Dissertation

Degree Name

Doctor of Philosophy in Biological Sciences (PhD)

Administrative Home Department

Department of Biological Sciences

Advisor 1

Erich J. Petushek

Advisor 2

John J. Durocher

Committee Member 1

Kelly Steelman

Committee Member 2

Robert A. Larson

Abstract

There has been a higher prevalence of developing anxiety due to frequent episodes of stress among adults in recent years. Chronic anxiety can contribute to the prevalence of elevated blood pressure and hypertension. High anxiety and stress also contribute to overactivation of the sympathetic nervous system which can be quantified by increased muscle sympathetic nerve activity (MSNA). Sympathetic overactivation can lead to vasoconstriction and loss of arterial elasticity. Anxiety, MSNA, blood pressure, and arterial stiffness are all interconnected, thus studying these relationships is crucial to understand the underlying mechanisms for prevention and treatment of cardiovascular disease (CVD). Non-pharmacological and mind-body treatments such as mindfulness-based stress reduction (MBSR) and stress management education (SME) have gained popularity in the management of anxiety and CVD risk.

In Study 1, 19 volunteers (18-45 years) were randomized into 8-week MBSR or SME, where we monitored changes in anxiety, decentering, and arterial stiffness. There was a tendency for state anxiety to be reduced after MBSR (p=0.06), but carotid-femoral pulse wave velocity (cfPWV) did not change from pre to post in either condition. Study 2 enrolled 27 volunteer participants (25±1 years) to determine how muscle sympathetic nerve activity (MSNA) and mean arterial pressure (MAP) reactivity influence post mental stress aortic augmentation index (AIx). The mental stress task significantly increased HR (Δ15±2 beats/minute), MAP (Δ14±1 mmHg), and perceived stress (Δ1.9±0.1 a.u.), while MSNA (Δ -13 to +20 bursts/min) was not significantly increased. The change in MAP during mental stress was a significant predictor (ꞵ=0.47; p=0.03) of the change in AIx (post-stress vs. baseline). Changes in MSNA and perceived stress were not predictors of mental stress-related changes in AIx. Study 3 examined how 8-week MBSR, or SME influenced anxiety and decentering in 36 volunteer participants. Nineteen participants completed the 8-week study prior to concerns over COVID-19 (no pandemic group = NPG), while 17 participants were affected by the stay-at-home order due to the pandemic (pandemic group = PG). Anxiety and decentering were measured before and after the 8-weeks of MBSR and SME. Trait anxiety was reduced in NPG/PG and MBSR/SME (pp<0.03).

The results of these studies agree with previous studies that indicate how MBSR can help to reduce anxiety. However, MBSR does not appear to decrease arterial stiffness (cfPWV). Aim 2 challenges the concept that acute stress-induced changes in aortic augmentation index are directly linked to changes in MSNA. The changes in AIx were linked to changes in MAP, but not MSNA. Aim 3 provides indications of how MBSR and SME can reduce trait anxiety and improve the ability to decenter during a global health crisis like COVID-19.

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