Brain anatomical correlates of mobility control in the oldest old

描述(申请人提供)：居住在社区的老年人经常报告与心肺、肌肉骨骼、外周和中枢神经系统的多因素变化有关的行动能力障碍。有强有力的紧急证据表明，白质(WM)高信号与独立于其他因素的下肢活动受限有关。罗萨诺博士最近发现，速度和平衡受损与特定活动相关区域的灰质(GM)局灶性萎缩有关。这一纵向流行病学项目旨在从健康老龄化身体成分研究(Health ABC)中调查GM和WM的局灶性脑磁共振成像(MRI)异常与与年龄相关的步速和平衡活动障碍的纵向关联。这项建议建立在目前正在进行的健康大脑项目(K23AG028966-01，PI：Dr Rosano)的基础上，该项目是一项描述性横断面研究，对健康ABC队列中250名参与者的定量大脑磁共振测量与机动性之间的关系进行了研究。我们建议的这项新研究将通过获得额外的148个磁共振成像设备来增强检测重要影响的能力，并将通过增加完成脑MRI后3年的跟踪时间，进一步深入了解脑MRI异常对行动能力障碍自然历史的影响。因此，在2006-2007年计划的健康ABC研究的数据收集阶段，这项提议的时机是独一无二的，以获取重要信息。该项目使用自动体积方法、磁化转移和扩散张量成像来测量GM和WM异常的严重程度和位置。本项目的目标是：1.研究局灶性GM和WM束异常与活动能力恶化的纵向联系，特别是与步态速度和平衡的关系。2.观察不同GM/WM异常组合对恶化速度和平衡能力的影响。3.确定心血管危险因素与活动相关区域和束的局灶性GM和WM异常的纵向关联。该项目的结果将促进我们对社区老年人行动能力障碍发病机制的了解，并将为进一步研究与行动能力控制有关的神经网络的年龄相关变化奠定基础，例如使用脑功能磁共振研究。

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.