Effects of cognitive challenge on gait control in elderly fallers

描述(由申请人提供)：这项建议的长期目标是开发筛查工具，以早期识别老年人未来跌倒的风险，并评估将抵消潜在病理过程的新的治疗干预措施。跌倒是一个主要的健康问题，需要努力解决老年跌倒者步态不稳的原因。越来越明显的是，走路与行政职能密切相关。使用双重任务范式的研究表明，执行力的变化在跌倒的原因路径中起到了作用。在双重任务范式中，当注意力要求高的任务和走路分别进行时，对它们的表现进行评估。此外，在步行过程中，从一步走到下一步的细微但重要的波动似乎是跌倒风险的敏感标志。可能是认知衰退导致了步幅变异性的这些变化，但这一点还没有被研究。目标。通过使用双重任务范式，这项建议将：1/调查步态中步幅变异性与并发认知任务难度之间U型关系的可行性，2/理清步幅变异性的具体方面(例如步幅与步长变异性)与执行功能的组成部分(例如工作记忆、反应抑制和认知灵活性)之间的相互关系，以及3/比较不同训练策略的效率，以了解老年跌倒者步幅变异性控制训练相关变化的潜在机制，并制定有针对性的预防跌倒的干预措施。K99期(横断面研究)。42名健康的年轻人、42名没有跌倒的老年患者和42名跌倒的老年患者将接受包括不同难度水平和挑战各种执行功能能力的认知任务的评估。参与者将在没有在跑步机上行走和在跑步机上行走的情况下接受听觉和语言任务的测试。我们预测步幅-步幅可变性的1/每个互补方面与认知负荷呈U型相关，并且功能的转折点发生在老年跌倒者比年轻和老年非跌倒者更低的认知负荷时，而在单任务和双任务步行条件下，更“中心”受损的2/2跌倒者将表现出不同于更“感觉”受损的跌倒者不同的行走轮廓。R00期(双臂随机对照试验)。将为总共142名老年跌倒者再招募100人，并随机分配到单任务步行训练和结合步行和认知负荷的双任务训练中。所有受试者都将在三个月的训练期之前和之后进行评估，并在六个月的随访期之后，在增加了新的双重任务的情况下，在实验1中使用的条件下进行评估。我们预测，双任务训练在定义跌倒风险分布和开发与特定执行功能缺陷相关的治疗策略方面将比单任务训练更好。方法：研究方法。行走性能将使用步幅到步幅的可变性和传统的生物力学测量来评估。对于R00试验，行走能力评估将基于两项选定的衡量标准，一项主要与中枢神经损伤有关，另一项主要与K99研究期间确定的与跌倒风险密切相关的感觉障碍有关。 与公共健康相关：跌倒的风险可能与大脑功能的某些方面的变化有关。这项研究试图开发工具来识别有跌倒风险的老年人。在双重任务条件下行走可能有助于在临床前阶段检测行走障碍，并计划有针对性的治疗干预以防止跌倒。

DESCRIPTION (provided by applicant): The long-term objective of this proposal is to develop screening tools for early identification of future fall risk in the elderly and to evaluate new therapeutic interventions that would counteract the underlying pathological process. Falls are a major health concern and efforts are needed to address the causes of gait unsteadiness in elderly fallers. It is increasingly clear that walking is tightly linked to executive functioning. Investigations using dual-tasking paradigms, where performance on attention-demanding tasks and walking is evaluated when they are performed separately and concurrently, suggest that executive changes play a role in the causal pathway of falls. Furthermore, the subtle but important fluctuations present from one stride to the next during walking seem to be sensitive markers of fall risk. It is possible that cognitive decline is responsible for these changes in stride-to-stride variability, but this has not been investigated. Objectives. Through the use of dual-task paradigms, this proposal will: 1/ investigate the viability of the U-shaped relationship between stride-to-stride variability during gait and difficulty of concurrent cognitive tasks, 2/ disentangle the interrelationships between specific aspects of stride-to-stride variability (e.g., stride width variability vs. step length variability) and components of executive function (e.g., working memory, response inhibition, and cognitive flexibility), and 3/ compare the efficiency of different training strategies to understand the mechanisms underlying training-related changes in stride-to-stride variability control of elderly fallers and develop targeted intervention for preventing falls. K99 phase (cross-sectional study). Forty two healthy young adults, forty two elderly non-fallers, and forty two elderly fallers will be assessed with cognitive tasks involving different levels of difficulty and challenging various executive functioning abilities. Participants will be tested with auditory and linguistic tasks without and with walking on the treadmill. We predict that 1/ each complementary aspect of stride-to-stride variability is related in a U- shaped manner to cognitive load and that the turning point of the function occurs at a lower cognitive load for elderly fallers than for young and elderly non-fallers, and 2/ fallers more "centrally" impaired would show different walking profiles than fallers more "sensory" impaired under both single and dual-task walking conditions. R00 phase (two-arm randomized controlled trial). One hundred more individuals will be recruited for a total of 142 elderly fallers and randomly assigned to a single-task walking training and a dual-task training combining walking and cognitive loading. All subjects will be evaluated before and after a three-month training period, and after a six-month follow-up period under the conditions utilized in Experiment 1 with the addition of novel dual tasks. We predict that dual-task training will be better than single-task training in defining fall-risk profiles and developing therapeutic strategies that are relevant to specific executive function deficits. Methods. Walking performance will be assessed using stride-to-stride variability and traditional biomechanical measures. For the R00 trial, walking performance assessment will be based on two selected measures, one primarily related to central nervous impairments and another one primarily related to sensory impairments that are strongly correlated with the risk of falling, as determined during the K99 study. PUBLIC HEALTH RELEVANCE: Risk of falls may be related to changes in certain aspects of brain function. This research seeks to develop tools to identify older people at risk for falls. Walking under dual-task conditions could be helpful in detecting walking disorders at a preclinical stage and planning targeted therapeutic interventions to prevent falls.