Aging with a Traumatic Brain Injury: Implications for Balance Deficits and Fall Risk

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Accumulating research indicates that a TBI sustained in early or middle adulthood has the potential to influence the trajectory of the aging process, both in the context of brain function and whole-body health. People who consider themselves to be fully recovered and asymptomatic many years following a brain injury might actually exhibit poorer function than peers who did not experience a head injury. The TBI literature reveals compelling evidence that TBI can elicit long-term abnormal cascades of neuroendocrine and neuroinflammatory processes that alter the structural and functional integrity of brain networks. However, there is little direct evidence to establish whether “normal” age-related neurodegeneration and decline of physical and cognitive function are made worse by a TBI that occurred many years earlier. By understanding the chronic effects of “aging with a TBI” we can better identify potential interventions to reduce negative repercussions across the lifespan. This is an important area of investigation, considering there is a substantial window of opportunity for Veterans who have experienced a TBI to engage in rehabilitative interventions and lifestyle modifications that may preserve function as they transition to older age. The overarching hypothesis of this new line of research is that participants who experienced a moderate TBI in early or middle adulthood (at least 15 years prior to study enrollment) will have poorer performance on balance and cognitive tests, despite self-reporting no persistent motor or cognitive impairment from the TBI. We also seek to evaluate the potential for practice-based learning and improvement of complex balance tasks in this population, in order to gain experience for conducting future rehabilitation studies. Veterans with prior TBI (TBI+ group) will be compared to a control group who report no history of TBI (TBI- group). We propose to enroll Veterans who are transitioning into older age (i.e., age between 50-65 years). This study will focus on balance function because of its close association with fall risk. Falls and resultant injuries are a major cause of disability in older Veterans and civilians, which poses a substantial rehabilitation demand and cost to individuals and society. The significance of balance deficits and falls will only grow in the coming years, as more than 50% of all Veterans will be 65 years or older by 2050. Further, loss of balance is very common in the acute stage of recovery from TBI, suggesting damage to neural control pathways/networks that might be susceptible to chronic effects. As secondary outcomes, we will conduct assessments that are related to balance function (including cognitive and oculomotor function) and that increase the risk of injuries due to a fall (bone mineral density). The TBI literature suggests that these secondary outcomes are also susceptible to the chronic effects of a TBI. The first aim of the study is to determine if TBI+ participants have impaired balance, cognition, and oculomotor performance compared to TBI- participants. The second aim of the study is to evaluate the potential for practice-based learning of balance tasks requiring visuospatial cognitive engagement. In addition to the proposed group analyses, we will also conduct exploratory regression analysis within the TBI+ participants to examine potential relationships between the severity of injury and continuous measures of motor and cognitive performance. The knowledge and experience gained from this study will prepare us to conduct larger studies to better understand the chronic effects of aging with a TBI, as well as prepare us to test rehabilitation interventions to promote healthy aging in this population.