Neuromechanisms of falls in older adults with MCI: Targeting assessment and training of reactive balance control

轻度认知障碍（MCI）沿着从正常认知到痴呆的连续体发生，几乎影响 70-79岁的人中有四分之一，患病率每十年急剧增加。虽然 大多数患有MCI（OAwMCI）的老年人在日常生活中是独立的，他们被认为具有显著的 福尔斯跌倒的可能性更大。除了认知缺陷， 患有MCI的人可能经历运动功能障碍，包括步态和平衡的缺陷。虽然变化 站姿控制和步态功能已经在这一人群中进行了彻底的研究， 平衡控制和保护性步进反应，以从不可预测的，更大的 外部扰动尚未得到广泛研究。此外，尽管OAwMCI显示较慢， 与他们的健康同行相比，适应和运动学习，仍然是未知的， OAwMCI可以通过反复暴露于不可预测的扰动来适应特定任务的训练， 老年人（OA）。此外，OAwMCI具有更差的双任务性能 在站立和步态中。这种表现与受损的执行功能，视觉功能 空间意识。然而，双任务的表现，在扰动的立场和步态与 在OAwMCI中尚未研究增加的跌倒风险。此外，众所周知， 皮质中枢在反应性平衡控制的调节中起着至关重要的作用。有趣的是，在OAwMCI中， 在感觉和认知挑战下的意志平衡控制与增加的静息状态相关 默认模式网络的激活、减少的白色物质完整性和减少的灰质体积。 然而，有有限的证据检查受损的结构完整性和 神经与反应性平衡控制措施相关，导致在此过程中福尔斯的发生率更高。 人口我们以前的研究表明，两个关键变量，反应控制的稳定性和垂直 肢体支撑，导致超过90%的OA实验室滑倒。因此，改善这些关键变量 有助于显著降低OA患者的跌倒风险。然而，这种基于特定任务干预的研究 在MCI人群中缺乏。为了填补文献中的差距，我们的研究建议调查 反应性步进对外部诱导平衡扰动的神经力学差异 与OA相比，OAwMCI。此外，我们的研究建议将无功稳定控制与 大脑结构和功能的连接。最后，我们的研究建议确定一个新的任务的效果- 基于特定扰动的认知运动干预，以增强OAwMCI患者的抗跌倒技能。

Mild cognitive impairment (MCI) occurs along a continuum from normal cognition to dementia and affects nearly a quarter of individuals 70-79 years old, with the prevalence drastically increasing each decade after. Although most older adults with MCI (OAwMCI) are independent in their daily living, they are known to have significantly greater likelihood of falls compared to their cognitively intact counterparts. In addition to cognitive deficits, persons with MCI can experience motor dysfunction, including deficits in gait and balance. While changes in stance posture control and gait functionality have been thoroughly investigated in this population, reactive balance control and protective stepping responses that are recruited to recover from unpredictable, larger external perturbations have not yet been extensively examined. Additionally, though OAwMCI show slower adaptation and motor learning in comparison to their healthy counterparts, it remains to be unknown whether OAwMCI can adapt to task-specific training via repeated exposure to unpredicted perturbations as healthy older adults (OA) do. Furthermore, it is well established that OAwMCI have worse dual-task performance during both stance and gait. This presentation is related to impaired executive function, visuomotor function and spatial awareness. However, dual-task performance during perturbed stance and gait in association with increased fall-risk has not yet been investigated in OAwMCI. In addition, it is well-established that higher cortical centers play a vital role in modulation of reactive balance control. Interestingly, in OAwMCI, the decline in volitional balance control under sensory and cognitive challenges is corelated to an increased resting state activation of the default mode network, reduced white matter integrity and reduced gray matter volume. However, there is limited evidence examining the association between impaired structural integrity and neural correlates with reactive balance control measures and resulting higher occurrence of falls in this population. Our previous research has shown that two key variables, reactive control of stability and vertical limb support, contribute to more than 90% of laboratory slip-falls in OA. Thus, improving these key variables can contribute to significant reduction in fall risk in OA. However, such task-specific intervention-based studies are lacking in the MCI population. To fill the gap in the literature, our study proposes to investigate the differences in neuromechanics of reactive stepping responses to externally-induced balance perturbations in OAwMCI compared to OA. Further, our study proposes to relate reactive stability control to changes in brain structural and functional connectivity. Lastly, our study proposes to determine the effect of a novel task- specific perturbation-based cognitive-motor intervention for enhancing fall-resisting skills in OAwMCI.