Effects of cognitive challenge on gait control in elderly fallers

描述（由申请人提供）：本提案的长期目标是开发早期识别老年人未来跌倒风险的筛查工具，并评估新的治疗干预措施，以抵消潜在的病理过程。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。越来越清楚的是，走路与执行功能密切相关。使用双任务范式的调查表明，执行能力的变化在跌倒的因果通路中起作用。双任务范式中，对注意力要求任务和行走的表现进行评估，当它们分别和同时执行时。此外，在行走过程中，从一步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。有可能是认知能力下降导致了这些跨步变异性的变化，但尚未对此进行研究。目标。通过使用双任务范式，本提案将：1/研究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（如步幅宽度变异性与步长变异性）与执行功能组成部分（如工作记忆、反应抑制和认知灵活性）之间的相互关系；3/比较不同训练策略的效率，了解训练相关的老年跌倒者跨步变异性控制变化的机制，制定针对性的跌倒预防干预措施。K99期（横断面研究）。研究人员将对42名健康的年轻人、42名不摔倒的老年人和42名摔倒的老年人进行认知任务评估，这些任务涉及不同难度和挑战各种执行功能能力。参与者将在没有跑步机和在跑步机上行走的情况下接受听觉和语言测试。我们预测，步幅变异性的每一个互补方面都与认知负荷呈U型关系，老年跌倒者的功能拐点发生在认知负荷较低的情况下，而在单任务和双任务行走条件下，“中枢”功能受损的跌倒者与“感觉”功能受损的跌倒者表现出不同的行走特征。R00期（两组随机对照试验）。总共142名老年跌倒者将被招募100多人，随机分配到单任务步行训练和双任务步行和认知负荷训练。在三个月的训练前后和六个月的随访期后，所有受试者将在实验1中使用的条件下进行评估，并增加新的双重任务。我们预测，在确定跌倒风险概况和制定与特定执行功能缺陷相关的治疗策略方面，双任务训练将优于单任务训练。方法。步行表现将通过跨步变异性和传统的生物力学测量来评估。对于R00试验，步行性能评估将基于两个选定的测量，一个主要与中枢神经损伤有关，另一个主要与感觉损伤有关，这与K99研究中确定的跌倒风险密切相关。

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.