Cognitive training and dual-task ability in older adults

描述(由申请人提供)： 在这十年中，85岁以上的退伍军人人数增加了两倍(美国退伍军人事务部，2007年)。已经证明，跌倒的速度在75岁以后翻一番(Hausdorff，2001)。考虑到跌倒的发生率随着年龄的增长而增加，以及相关的发病率，这项研究对老年退伍军人具有重要意义。从历史上看，老年人平衡控制的退化被归因于运动和/或感觉系统的损害。因此，治疗的重点是运动和感觉障碍。然而，证据表明，在双重任务情境中分配注意力资源以保持平衡的能力受损是跌倒的有力预测因素(Verghese，2002)。尽管如此，很少有研究研究干预是否可以提高老年人的双重任务能力。本研究的目的是开发有效的干预措施，以提高在双重任务条件下分配注意力到平衡和步态的能力。研究表明，老年人的双重任务表现可以得到改善；然而，大多数研究都是在非平衡相关任务中进行的(Rogers和Fisk，2001)。少量干预提供了唯一的证据，证明了训练的有效性，以提高步态任务中分散注意力的能力。Silsupadol等人。(2009a，2009b)发现，只有在双重任务条件下训练的参与者在双重任务条件下的步态有所改善。相反，Hall和Heusel-Gillig(2010)发现，在没有特殊的双重任务训练的情况下，平衡康复可以改善双重任务条件下的步态。需要进一步研究以确定最佳平衡康复参数。因此，这项研究的第一个目的是检验双重任务练习在多大程度上改善了双重任务条件下的步态。一种新的改善步态的方法是通过增强认知功能。通过使用改善认知的药物，药物干预已经证明了对步态的积极影响(Auriel，2006)。最近的发现表明，特定的认知能力(处理速度、注意力和执行控制)与在双重任务条件下行走的能力有关(Hall，出版社；Holtzer，2006)。有大量证据表明，认知训练可以改善老年人的这些特定认知能力(Ball，2002)。目前尚不清楚这种认知方面的改善是否会在双重任务条件下增强步态。因此，这项研究的另一个目标是考察认知训练对双重任务能力的益处程度。具体目标1审查纳入标准平衡康复的双重任务练习在多大程度上会给双重任务能力带来更大的好处。假设1a：在包括双任务活动的平衡康复之后，双任务条件下的行走将有更大的改善。假设1b：运动能力的提高将解释双重任务条件下行走能力改善的很大一部分差异。具体目标2考察平衡康复后的认知训练在多大程度上对双重任务能力产生更大的好处。假设2a：在认知训练之后，在双重任务条件下行走的能力将有进一步的改善。假设2b：与一般认知训练相比，在加工速度训练后的双重任务条件下行走会有更大的好处。假设2c：认知能力的提高将在很大程度上解释双重任务条件下行走能力进一步改善的原因。44名老年人(n=44)因步态或平衡障碍而接受物理治疗(PT)，他们有双重任务障碍(基于已公布的减法任务计时起跑测试标准)，将随机接受标准平衡康复或双任务练习平衡康复。在PT之后，受试者将接受认知训练(CT)，要么是加工速度训练，要么是广义认知训练。主要结果是在执行四种不同难度的不同认知任务时行走的能力。评估将在基线上进行， PT后，CT后。

DESCRIPTION (provided by applicant): The number of veterans over 85 years of age has tripled during this decade (US Dept of Veterans Affairs, 2007). It has been demonstrated that the rate of falls doubles after age 75 (Hausdorff, 2001). Given the increased incidence of falls with age and associated morbidity, this study has significance to aging veterans. Historically, degradation of balance control in older adults has been attributed to impairments of the motor and/or sensory systems. As a result, therapy has focused on motor and sensory impairments. However, evidence suggests that an impaired ability to allocate attentional resources to balance during dual-task situations is a powerful predictor of falls (Verghese, 2002). Despite this fact, few studies have examined whether interventions can improve older adults' dual-task ability. The goal of this study is to develop effective interventions to improve ability to allocate attention to balance and gait under dual-task conditions. Studies have shown that dual-task performance by older adults can be improved; however, the majority of research has been in non-balance related tasks (Rogers and Fisk, 2001). Interventions with small numbers provide the only evidence for the effectiveness of training to improve ability to divide attention in gait tasks. Silsupadol et al. (2009a, 2009b) foud that only participants trained under dual-task conditions showed improvements in gait under dual-task conditions. In contrast, Hall and Heusel-Gillig (2010) found that balance rehabilitation with no specific dual-task training resulted in improved gait under dual-task conditions. Further research is warranted to determine optimal balance rehabilitation parameters. Thus, the first aim of the study is to examine the extent to which the addition of dual-task practice improves gait under dual-task conditions. A novel approach to improving gait is through the enhancement of cognitive function. Pharmacologic interventions have demonstrated a positive effect on gait by the use of drugs that improve cognition (Auriel, 2006). Recent findings suggest that specific cognitive abilities (speed of processing, attention, and executive control) are associated with ability to walk under dual-task conditions (Hall, in press; Holtzer, 2006). There is substantial evidence that cognitive training can improve these specific cognitive abilities in older adults (Ball, 2002). It is unknown whether such improvements in cognition would enhance gait under dual-task conditions. Thus, another goal of the study is to examine the extent to which cognitive training benefits dual-task ability. Specific Aim 1 Examine the extent to which the inclusion of dual-task practice to standard balance rehabilitation results in greater benefits to dual-task ability. Hypothesis 1a: There will be greater improvement in walking under dual-task conditions following balance rehabilitation that includes dual-task activities. Hypothesis 1b: Improved motor abilities will explain a significant proportion of the variance of improved ability to walk under dual-task conditions. Specific Aim 2 Examine the extent to which the addition of cognitive training following balance rehabilitation results in greater benefits to dual-task ability. Hypotheis 2a: There will be additional improvements in the ability to walk under dual-task conditions following cognitive training. Hypothesis 2b: There will be greater benefits to walking under dual-task conditions following speed of processing training versus general cognitive training. Hypothesis 2c: Improved cognitive abilities will explain a significant proportion of the variance o further improvements in walking under dual-task conditions. Older adults (n = 44) who have been referred to physical therapy (PT) for gait or balance impairments who have dual-task impairment (based on published criteria for the timed up and go test with a subtraction task) will be randomized to receive either standard balance rehabilitation or balance rehabilitation with dual-task practice. Following PT, subjects will receive cognitive training (CT), either speed of processing or generalized cognitive training. Primary outcomes are ability to walk while performing four different cognitive tasks of varying difficulty. Assessment will occur at baseline, post-PT, post-CT.