Psychosocial Factors and Aging: Resting/Reflexive Cardiovascular Control

描述（由申请人提供）：几十年来，我们已经知道较低的心率（HR）与发病率和死亡率降低有关。但HR并不稳定--它本质上是“嘈杂的”，在均值附近振荡。从20世纪80年代开始，这些振荡的临床和生理意义，现在被称为心率变异性（HRV），已经被认识到。HRV预测心肌梗死或心力衰竭诊断后的不良结局、CAD患者动脉粥样硬化的进展以及健康社区样本中CAD的发展。因此，HR中的测量“噪声”现在被认为是心血管健康的有价值的指标。 今天，血压（BP）处于与40年前HR相似的位置。虽然平均血压（BP）的临床意义已经被接受了几十年，但受试者内BP在多个时间尺度上变化很大。曾经被视为噪音的BP变异性（BPV）现在也被认为包含有价值的信息。在数周甚至数年内重复测量，门诊间血压的标准差（SD）可预测12-14年随访后高血压的发展和死亡率。在24小时量表上，每30分钟测量一次的血压标准差与8.5年随访后的心血管死亡率和更大的靶器官损伤相关。在更短的时间尺度上，BP在逐搏的基础上变化。该领域的共识是，BPV的最终预后价值可能需要分析这些逐搏BP振荡。然而，由于测量这些更快速的振荡在技术上要求很高，尚未建立逐搏BPV与临床或与健康相关的心理社会变量的关联。技术进步使得逐搏BPV越来越可用，并且探索其与心血管健康和背景社会人口学和心理社会心血管风险因素的关系有可能产生重要的临床和生理见解。 测量逐搏BP沿着RR间期还允许计算压力反射敏感性（BRS），即RR间期的反射性变化与BP变化的关系。虽然BPV可能代表紧张性自主神经指数，但BRS是预测MI和心力衰竭后不良结局的自主神经反射指数。然而，据我们所知，BPV和BRS的社区研究并不存在。 我们建议分析已经收集但未分析的心跳BP数据，这些数据来自美国中年（MIDUS II）研究中第2波数据收集的参与者在休息时以及对心理和直立性挑战的反应。本研究的目的是在探索性前瞻性分析中检查静息和反应性BPV和BRS与各年龄段的心理社会和生物标志物数据之间的关系，以检验更高的BPV和更低的BRS是否与更高的死亡率相关。

DESCRIPTION (provided by applicant): For decades, we have known that lower heart rate (HR) is associated with reduced morbidity and mortality. But HR is not stable - it is inherently "noisy," oscillating around the mean. Beginning in the 1980s, the clinical and physiological significance of these oscillations, now known as Heart Rate Variability (HRV), has been recognized. HRV predicts adverse outcomes following myocardial infarction or diagnosis of heart failure, progression of atherosclerosis in CAD patients, and the development of CAD in healthy community samples. Thus, measurement "noise" in HR is now recognized as a valuable index of cardiovascular health. Today, blood pressure (BP) is in a similar position as HR was 40 years ago. While the clinical significance of mean blood pressure (BP) has been accepted for decades, within-subject BP varies considerably across multiple time scales. Once dismissed as noise, BP variability (BPV) now also is thought to contain valuable information. Measured repeatedly over weeks or even years, the standard deviation (SD) of clinic-to-clinic BP predicted the development of hypertension and mortality after 12-14 years follow-up. On a 24-hour scale, the SD of BP measured every 30 min was associated with cardiovascular mortality after 8.5 years follow-up and with greater target organ damage. At a still shorter time scale, BP varies on a beat-to-beat basis. Consensus in the field is that the ultimate prognostic value of BPV may require analysis of these beat-to-beat BP oscillations. However, because measurement of these more rapid oscillations has been technically demanding, associations of beat-to-beat BPV with clinical or with psychosocial variables linked to health have not been established. Technological advances have made beat-to-beat BPV increasingly available and exploration of its relationship to cardiovascular health and contextual sociodemographic and psychosocial cardiovascular risk factors has the potential to yield important clinical and physiological insights. Measuring beat-to-beat BP along with RR intervals also allows for computation of baroreflex sensitivity (BRS), the relationship of reflexive changes in RR interval to changes in BP. While BPV may represent a tonic autonomic index, BRS is an index of autonomic reflexes that predicts adverse outcomes after MI and in heart failure. However, to our knowledge, community studies of BPV and BRS do not exist. We propose to analyze the beat-to-beat BP data already collected but not analyzed from participants at rest and in response to psychological and orthostatic challenge from the wave 2 of data collection in the Midlife in the US (MIDUS II) study. Our aims in this R21 are to examine relationships between resting and reactive BPV and BRS and psychosocial and biomarker data across the age spectrum and in an exploratory prospective analysis, to test whether greater BPV and lower BRS are associated with greater mortality.