Association of remote mild traumatic brain injury with cortical amyloid burden in clinically normal older adults

We investigated whether clinically normal older adults with remote, mild traumatic brain injury (mTBI) show evidence of higher cortical A beta burden. Our study included 134 clinically normal older adults (age 74.1 +/- 6.8 years, 59.7% female, 85.8% white) who underwent A beta positron emission tomography (A beta-PET) and who completed the Ohio State University Traumatic Brain Injury Identification questionnaire. We limited participants to those reporting injuries classified as mTBI. A subset (N = 30) underwent a second A beta-PET scan (mean 2.7 years later). We examined the effect of remote mTBI on A beta-PET burden, interactions between remote mTBI and age, sex, and APOE status, longitudinal A beta accumulation, and the interaction between remote mTBI and A beta burden on memory and executive functioning. Of 134 participants, 48 (36%) reported remote mTBI (0, N = 86; 1, N = 31, 2+, N = 17; mean 37 +/- 23 years since last mTBI). Effect size estimates were small to negligible for the association of remote mTBI with A beta burden (p = .94, eta(2) < 0.01), and for all interaction analyses. Longitudinally, we found a non-statistically significant association of those with remote mTBI (N = 11) having a faster rate of A beta accumulation (B = 0.01, p = .08) than those without (N = 19). There was no significant interaction between remote mTBI and A beta burden on cognition. In clinically normal older adults, history of mTBI is not associated with greater cortical A beta burden and does not interact with A beta burden to impact cognition. Longitudinal analyses suggest remote mTBI may be associated with more rapid cortical A beta accumulation. This finding warrants further study in larger and more diverse samples with well-characterized lifelong head trauma exposure.

Automated summary

In clinically normal older adults, a history of mTBI is not associated with higher cortical A beta burden and does not interact with A beta burden to affect cognition. However, remote mTBI may be linked to a faster rate of A beta accumulation.