Association Of Cardiorespiratory Fitness And Cognitive Function In Persons With Traumatic Brain Injury

Cognitive dysfunction is a common symptom of traumatic brain injury (TBI) that directly affects everyday life and varies greatly across people. Aerobic exercise training (AET) can improve many cognitive domains at once, based on extensive evidence for small, reliable benefits of AET on cognition in healthy older adults. These studies were designed to target cognitive domains that were associated with cardiorespiratory fitness (CRF). Studies on AET for cognition in TBI report equivocal results, likely due to inappropriate cognitive outcome measure selection. PURPOSE: To measure the relationship between CRF and objective neuropsychological assessments (NPs) in persons with TBI. METHODS: During a single session, adults with a TBI ≥1 year prior completed a small battery of NPs and a cardiopulmonary exercise test (CPET). NPs included the California Verbal Learning Test-II (CVLT-II), Symbol Digit Modalities Test (SDMT), and Wechsler Adult Intelligence Scale Letter Number Sequencing (LNS). The CPET used a ramp protocol (i.e., 15 watts/minute) on a cycle ergometer with a target cadence of 40-60 RPM. Spearman’s rho one-tailed rank-order correlations (ρ) were performed on CRF (i.e., peak power output [Wpeak] and peak oxygen uptake [VO2peak]) and NPs. RESULTS: Twenty-four persons (male n = 16; mean age = 43.46 ± 13.76) who had a TBI 12.42 ± 12.68 years prior completed testing. Wpeak was positively associated with retention, measured by the CVLT-II (ρ = 0.473, p = 0.010), and was trending toward significance with processing speed, measured by the SDMT (ρ = 0.290, p = 0.085). VO2peak was trending toward significance with retention (ρ = 0.274, p = 0.098), processing speed (ρ = 0.285, p = 0.089), and working memory, measured by the LNS (ρ = 0.275, p = 0.097). CONCLUSION: There is a trending or better relationship between CRF and memory, processing speed, and working memory in persons with TBI. This sample is underpowered to detect most statistically significant associations. Data collection is ongoing, and upon completion, we anticipate being sufficiently powered. Regardless, these trends warrant future research on the associations between CRF and cognitive functions to directly inform future exercise-based rehabilitation techniques to improve cognitive dysfunction following TBI.