Nonlinear Dynamics of Frailty in Aging

在过去的20年里，我们使用非线性动力学和分形分析工具进行了协作工作，我们的研究 研究小组已经证明，衰老和疾病与多种疾病动力学中复杂性的丧失有关 生理系统。我们已经提出，这种复杂性的丧失会导致适应能力的降低，功能性 衰落，脆弱。可以量化生理系统及其动力学的非线性数学技术 因此，相互作用可能有助于描述虚弱综合征的特征。因此，我们的目标是：1)确定交叉- 在70岁及以上的有代表性的老年人群体中，是否存在 在包括心血管在内的多个生理系统的动力学中的“脆弱”和复杂性的丧失之间 (心搏间期(RR)和血压(BP))、脑血管(脑血流速度(BFV))、呼吸 (呼吸间隔)和平衡(压力中心轨迹)控制系统。我们还将确定是否 在虚弱的老年人中，这些系统之间的相互作用通过检查相关性、连贯性、阶段 以及相互作用系统(例如，心脏和呼吸，或 全身血压和脑BFV)。2)确定心血管、脑血管、 和/或平衡动力学，与适应施加在身体上的常见生理压力的能力受损有关 这些系统。我们将具体检查：a)静息BP、RR间期或脑血之间的关系 流动动力学及其对姿态变化的响应，以及b)安静的站立压力中心轨迹及其 对叠加的认知任务的反应。3)在两年的纵向随访期内确定 同样的人群，无论这些生理系统在基线时动力学的复杂性降低，还是 随着时间的推移，这些系统中的复杂性预示着脆弱性的后续发展，其组件症状， 和/或身体和认知功能衰退的其他衡量标准。为了实现这些目标，我们将处理和分析 生理数据是从一个具有良好特征的、预期跟踪的、基于人群的 800名70岁以上的老年人参加了一项正在进行的NIA资助的计划项目赠款(The HRCA/哈佛研究疗养院，P01-AG004390)。课题组在临床老年病研究中的体会 研究、生理学、动力系统和生物统计学，以及希伯来语的优秀资源 康复中心和哈佛医学院将帮助确保该项目的成功。

Over the past 2 decades of collaborative work using the tools of nonlinear dynamics and fractal analysis, our research team has shown that aging and disease are associated with a loss of complexity in the dynamics of a variety of physiologic systems. We have proposed that this loss of complexitycan lead to reduced adaptive capacity, functional decline, and frailty. Nonlinear mathematical techniques that can quantify the dynamics of physiologic systems and their interactions may, therefore, help characterize the syndrome of frailty. Accordingly, we aim: 1) To determine cross- sectionally in a representative population of elderly people aged 70 years and over, whether there is a relationship between "frailty" and loss of complexity in the dynamics of multiple physiologic systems, including cardiovascular (interbeat (RR) intervals and blood pressure (BP)), cerebrovascular (cerebral blood flow velocity (BFV)), respiratory (interbreath intervals), and balance (center-of-pressure trajectories) control systems. We will also determine whether interactions between these systems degrade in frail elderly individuals by examining the correlations, coherence, phase, and transfer function gains between the dynamic measures of interacting systems (e.g., cardiac and respiratory, or systemic BP and cerebral BFV). 2) To determine whether a loss of complexity in cardiovascular, cerebrovascular, and/or balance dynamics, is associated with an impaired ability to adapt to common physiologic stresses imposed on these systems. We will examine specifically the relationships between: a) resting BP, RR intervals, or cerebral blood flow dynamics and their responses to posture change, and b) quiet standing center-of pressure trajectories and their response to a superimposed cognitive task. 3) To determine,longitudinally over a two-year follow-up period in the same population,whether reduced complexity in the dynamics of these physiologic systems at baseline, or loss of complexity in these systems over time, is predictive of the subsequent development of frailty, its component symptoms, and/or other measures of physical and cognitive functional decline. To achieve these aims we will process and analyze physiologic data that are being gathered from a well-characterized, prospectively followed, population-based sample of 800 elderly people over age 70 who are participating in an ongoing NIA-funded Program Project Grant (the HRCA/Harvard Research Nursing Home, P01-AG004390). The experience of the research team in clinical geriatric research, physiology, dynamic systems, and biostatistics, as well as the outstanding resources of the Hebrew Rehabilitation Center and Harvard Medical School will help assure the project's success.