Study of the Effects of Negative Emotions on Endothelial Function

Overview

Study aims and hypotheses are as follows: Primary Hypotheses: Compared to the neutral condition, the anger recall task will acutely induce endothelial dysfunction by impairing endothelium-dependent arterial vasodilation (Hypothesis 1a); increasing circulating levels of EC-derived microparticles (EMPs), a marker of EC injury (Hypothesis 1b); and reducing circulating levels of bone marrow-derived endothelial progenitor cells (EPCs), a marker of EC reparative capacity (Hypothesis 1c). Secondary Hypotheses: Compared to the neutral condition, the depressed mood and separately the anxiety recall tasks will acutely impair endothelium-dependent arterial vasodilation, increase circulating levels of EMPs, and reduce circulating levels of bone marrow-derived EPCs. There will be a relation of the level of self-reported anger, depressed mood, and anxiety with endothelial dysfunction.

Atherosclerosis-related cardiovascular disease (CVD) events remain the leading causes of morbidity and mortality in industrialized nations. Atherosclerosis is a diffuse disease characterized by the deposition of lipid and other blood-borne material within the arterial wall. Evidence demonstrates that disruption of an arterial atherosclerotic plaque and subsequent thrombus formation is responsible for the onset of CVD events. Cardiovascular research efforts have been directed toward the identification of early underlying factors that initiate this cascade. It has been known for some time that the experience of negative emotions is associated with an increased risk of incident CVD events, independent of traditional risk factors. Among the best-studied negative emotions is anger. Population-based studies have demonstrated that the experience of anger is a trigger of incident CVD events. The mechanism(s) by which provoked anger acutely affects the pathways that underlie atherosclerosis development and progression remain to be fully characterized. Endothelial dysfunction is a promising mechanism that may explain the link between anger and incident CVD events. Vascular endothelial cells (ECs) play essential roles in maintaining vascular tone and the integrity of blood vessels. Evidence suggests that endothelial dysfunction is an early pathogenic process underlying atherosclerosis development and CVD event onset. Our preliminary findings show in apparently healthy individuals, an anger recall task acutely induces endothelial dysfunction by impairing endothelium-dependent vasodilation, injuring ECs, and disrupting the molecular processes underlying EC reparative capacity. We have additionally found that this task may induce endogenous nitric oxide (NO) inhibition, which plays a central role in aggravating endothelial dysfunction. Therefore, NO inhibition may partially mediate anger-provoked endothelial dysfunction. Although the strongest data are on anger-provoked CVD events, there is also some evidence that the experience of other core negative emotions such as depressed mood and anxiety may trigger CVD events. Whether the provocation of depressed mood and anxiety acutely induces endothelial dysfunction and NO inhibition remains to be determined. The overall aim of this study is to primarily examine the acute effects of provoked anger and secondarily depressed mood and anxiety on EC health. We will also explore whether NO inhibition partially mediates the acute effects of anger, depressed mood, and anxiety on endothelial function. Examination of these critical pathways will help identify the biological pathways by which the experience of core negative emotions leads to incident CVD risk. To address these highly significant research questions, we propose a state-of-the-art, laboratory-based, randomized controlled experiment in which 280 participants will be randomized to one of four experimental conditions: an anger recall task (N=70), a depressed mood recall task (N=70), an anxiety recall task (N=70), and an emotionally neutral condition (N=70).