Objective
The broad objective of this study is to examine the effects of moderate and more intense aerobic exercise as an intervention on cognitive performance, physical functioning and health-related quality of life in patients with chronic (more than 12 months post-injury) traumatic brain injury (TBI). Importantly, structural and biological brain changes will be measured to examine whether functional outcomes are related to exercise-induced adaptations. It is hypothesized that in the chronic phase of persons with TBI, there will be improved: 1) cognitive function, 2) physical fitness and fatigue severity, 3) motor performance and balance, and 4) mood and depressive symptoms, in those that performed the exercise intervention compared to a control group. It is also hypothesized that these functional improvements will be related to exercise intensity, improved cortical connectivity, dopamine transmission gene scores, and blood biomarkers related to neuro and angio-genesis.
Study Population
80 ambulatory adults with non-penetrating TBI will be enrolled. We will also enroll up to 20 healthy volunteers as a comparison group for some of the outcome measures. Subjects will be recruited from NIH, affiliated hospitals/clinics and the community
Design
Healthy volunteers will have a limited assessment that includes brain imaging, blood draw for genetic testing, and a subset of the cognitive and behavioral testing at a single time-point. All subjects with TBI will perform baseline assessments including cognitive and behavioral performance, brain imaging, fitness, motor and balance testing, and selected blood and genetic testing. Thereafter, subjects with TBI will be randomized to either a waitlist control, or one of two exercise conditions: 1) 30 minutes at a fast pace, moderate-intensity (rapid-resistive exercise; RET); 2) 30 minutes at higher-intensity (aerobic exercise; AET). Both exercise groups will perform the exercise on an elliptical trainer 3 times a week, for a session duration of 45 minutes including warm-up and cool-down. The RET group will focus on rapid reciprocal motion with minimal resistance, while the AET group will exercise at an elevated intensity known to produce an aerobic effect. After 12 weeks, all groups will repeat the baseline assessments (3 month follow-up). Following this assessment, the waitlist control group will be randomized to either RET or AET and the exercise groups will cease formal supervised exercise sessions. A third assessment visit will be performed after an additional 12 weeks (6 month follow-up).
Outcome Measures
Cognitive performance will be tested and interpreted compared to norms. Performance on motor and balance tasks will be assessed with the Smart Balance Measurement System and the GAITRite System. Physical fitness will be determined by peak oxygen consumption and aerobic threshold as measured by pulmonary gas exchange during an exercise tolerance test on the treadmill. Structural brain volumes will be determined by magnetic resonance imaging (MRI) and cortical connectivity will be quantified using resting state functional MRI and Diffusion Tensor Imaging (DTI) to evaluate integrity of and changes in white matter tracts in response to exercise and compared to healthy volunteers. Blood will be collected to quantify the presence of biomarkers (such as VEGF, BDNF and IGF-1) and dopamine transmission. Other self-reported measures of quality of life, fatigue severity, depression and sleep quality would also be collected, and compared to healthy volunteers.
