Brain anatomical correlates of mobility control in the oldest old

描述（由申请人提供）：社区居住的老年人经常报告与心肺、肌肉骨骼、外周和中枢神经系统多因素变化相关的活动障碍。有强有力的证据表明，白色物质（WM）高信号与下肢活动受限相关，与其他因素无关。Rosano博士最近发现，速度和平衡受损与特定移动相关区域的局灶性灰质（GM）萎缩有关。这个纵向流行病学项目的目的是调查纵向关联的局灶性脑磁共振成像（MRI）异常，在GM和WM与年龄相关的运动障碍的步态速度和平衡在一个大的队列的社区居住的老年人的健康老化身体成分研究（健康ABC）。该提案建立在当前正在进行的健康大脑项目（K23 AG 028966 -01，PI：Rosano博士）的基础上，该项目是一项描述性横断面研究，旨在研究定量大脑MRI测量与健康ABC队列250名参与者的活动性之间的关联。我们提出的这项新研究将通过采集额外的148个MRI来增加检测重要影响的能力，并将通过在完成脑MRI后增加3年的随访时间，进一步纵向了解脑MRI异常对运动障碍自然史的影响。因此，这一建议的时间安排非常独特，以便在2006-2007年卫生ABC研究计划的数据收集阶段收集重要信息。该项目使用自动体积方法、磁化传递和扩散张量成像来测量GM和WM异常的严重程度和位置。该项目的目标是：1。检查局灶性区域GM和WM束异常与活动性恶化的纵向相关性，特别是与步态速度和平衡的相关性。2.检查GM/ WM异常组对速度和平衡恶化的综合影响。3.确定心血管危险因素与运动相关区域和束中局灶性GM和WM异常的纵向关联。该项目的结果将推进我们对社区居住老年人运动障碍发病机制的认识，并为进一步研究参与运动控制的神经网络的年龄相关变化奠定基础，例如使用功能性脑MRI研究。

DESCRIPTION (provided by applicant): Community-dwelling older adults often report mobility impairment linked with multifactorial changes in the cardiopulmonary, musculoskeletal, peripheral and central nervous systems. There is strong emergent evidence that white matter (WM) hyperintensities are associated with lower-extremity mobility limitations independent of other factors. Dr. Rosano has recently discovered that impaired speed and balance are associated with focal grey matter (GM) atrophy of specific mobility-related regions. This longitudinal epidemiological project aims to investigate the longitudinal association of focal brain magnetic resonance imaging (MRI) abnormalities in GM and WM with age-related mobility impairment in gait speed and balance in a large cohort of community-dwelling older adults from the Health Aging Body Composition Study (Health ABC). This proposal builds onto the current ongoing Healthy Brain Project (K23AG028966-01, PI: Dr Rosano), which is a descriptive cross-sectional study of the association between quantitative brain MRIs measures and mobility in 250 participants of the Health ABC cohort. The new study that we propose will increase the power to detect important effects via the acquisition of additional 148 MRIs and will provide further longitudinal insights into the impact of brain MRI abnormalities on the natural history of mobility impairment by adding a follow up time of 3 years after completion of brain MRI. Thus, this proposal is uniquely timed to capture important information during the planned data collection phase of the Health ABC Study in 2006-2007. This project uses automated volumetric methods, magnetization transfer and diffusion tensor imaging to measure severity and location of GM and WM abnormalities. The aims of this project are: 1. To examine the longitudinal association of focal regional GM and WM tracts abnormalities with worsening mobility and specifically with gait speed and balance. 2. To examine the combined effect of groups of GM/ WM abnormalities on worsening speed and balance. 3. To determine the longitudinal association of cardiovascular risk factors with focal GM and WM abnormalities in mobility-related regions and tracts. The results of this project will advance our knowledge of the pathogenesis of mobility impairment in community-dwelling older adults and will lay the ground work for further studies of age-related changes of the neural networks involved in mobility control, for example using functional brain MRI studies.