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.
Relevance of Proposed Research to VA Patient Care Mission This research directly addresses the mission of the VA by attending to quality-of-life mandates. The number of veterans age 85 years and older has tripled this decade (VetData, 2010). Older veterans, particularly those over 85, are among the most vulnerable of the veteran population and are at highest risk for suffering fall-related injuries. An estimate of outpatient costs to the VA in 2001 for fall-related injuries as nearly $3.3 million for the initial visit alone (Luther, 2005). The potential for large economic savings by reducing falls incidence, thus fall-related injuries, is evident. Given the increased incidence of falls with age and the morbidity associated with falls, the results of this study willbe relevant to a substantial number of veterans. The proposed study has the potential to develop novel rehabilitation approaches to reduce the risk of falls in older veterans. This project will contribute to improved management of fall risk, improved quality of life and to containing the cost of health care in the elderly.