Abstract
Background
Traumatic 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.
Method
79 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.
Result
25 (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.
Conclusion
The 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.