P2‐340: LASTING CONSEQUENCES OF CONCUSSION: BRAIN FINDINGS FROM THE BALTIMORE LONGITUDINAL STUDY OF AGING

Abstract

While recent studies have reported alterations in the structure and function of the brain following a concussive event, few have examined the long-term impact of concussions on the aging brain. Here, we examine these long-term effects, 20+ years after the incident. We used neuroimaging and neuropsychological data from 51 participants (mean age at neuroimaging baseline=65.1, SD=11.23) in the Baltimore Longitudinal Study of Aging (BLSA) who reported a concussion in their medical history an average of 22 years prior to first visit, and compared them to 150 age, sex, and race matched BLSA participants with no history of concussion. Participants underwent structural magnetic resonance imaging (MRI) over a mean of 5.17 years (SD=6.14) and diffusion tensor imaging (DTI) over a mean of 2.92 years (SD=2.22) to measure brain structure, as well as 15O-water Positron Emission Tomography (PET) over a mean of 5.33 years (SD=2.19) to measure brain function. A battery of neuropsychological tests was also administered over a mean of 11.62 years (SD=7.41). Structural MRI changes indicating brain atrophy were seen in temporal lobe white matter and hippocampus at first visit, and in the occipital pole during longitudinal follow-up. Structural differences in white matter integrity using DTI were seen with increased radial and axial diffusivity in the fornix/stria terminalis, and internal capsule at first visit, and in fractional anisotropy in the corona radiata during longitudinal follow-up. Functional differences were seen in 15O-PET resting cerebral blood flow at first visit and longitudinal follow-up in regions including the frontal, temporal, and parietal cortices. No significant differences in neuropsychological performance were seen between groups, but within the concussion group itself, there was a correlation between age at concussive event and visuospatial performance, with concussion sustained at older ages associated with lower performance levels at first visit. These findings indicate that a single concussion can produce subtle, long-lasting structural and functional changes to brain. As many of these regions are susceptible to age-related neuropathologic changes, these findings also suggest that individuals with a history of concussion may be more vulnerable to further dysfunction in these brain regions with advancing age.