Examining the relationship between mild traumatic brain injury, later‐life brain health and cardiorespiratory fitness in a community‐dwelling sample of older adults

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AbstractBackgroundTraumatic brain injury (TBI) has been recognised as an important global health priority. Mild traumatic brain injury (mTBI), also known as concussion, accounts for up to 90% of all TBI diagnoses. Accumulating evidence also suggests that mTBI may be a risk factor for later‐life cognitive decline and neurodegeneration, including Alzheimer’s disease and other forms of dementia. Physical activity and exercise have received increasing attention as a potentially cost‐effective mechanism to attenuate age‐related declines to cognitive functioning and brain volume. However, little is known about the interaction between maintaining a higher level of physical fitness later in life and its impact on markers of brain health in individuals with a history of mTBI in the general population.Method79 community‐dwelling older adults (mean age 68.72 ± 4.28 years, 54.4% female) underwent a comprehensive cardiorespiratory fitness assessment and magnetic resonance imaging. Participants also completed a retrospective mTBI history questionnaire.Result25 (32%) of the study participants reported sustaining at least one lifetime mTBI. No differences in total hippocampal or white matter volumes were found between participants who had a history of mTBI and those who did not. However, participants with a history of mTBI had, on average, a significantly higher total grey matter volume (581.16 ± 19.44) in comparison to controls with no mTBI history (570.05 ± 17.22), p = 0.005. Subsequent analyses found that cardiorespiratory fitness did not moderate the relationship between mTBI history and any of the MRI metrics examined.ConclusionThe results of this study suggest that later‐life cardiorespiratory fitness, in isolation, does not protect the brain from mTBI‐induced global or regional volumetric changes. Tracking longitudinal post‐mTBI physical activity habits will be critical to elucidating whether longer‐term cardiorespiratory fitness patterns are more influential in determining later‐life neurocognitive outcomes.