Author Response: Blood Biomarkers of Traumatic Brain Injury and Cognitive Impairment in Older Veterans

We would like to thank Drs. Wisniewski and Fossati for their insightful comments on our recent article1 examining blood biomarkers associated with traumatic brain injury (TBI) and cognitive impairment (CI) in CNS-enriched exosomes. We agree that our findings of differences between the TBI and CI groups do not seem to be solely due to TBI and are most likely explained by TBI-associated CI. Indeed, our results suggest that phosphorylated tau, neurofilament light, tumor necrosis factor alpha, interleukin 6, and glial fibrillary acidic protein could differentiate non–TBI-CI from TBI-CI. Drs. Wisniewski and Fossati astutely pointed out differences between 2 different biomarker articles published by our group. These studies used different assays analyzed in separate laboratories, and study participants were different, although overlapping. However, due to the small sample size, we cannot discount the possibility of type II error in our findings with regard to Aβ42. Nonetheless, our results—along with several other imaging and biomarker studies—suggest that TBI-CI is likely to differ from classic Alzheimer disease biomarkers. We appreciate the ability to clarify the results of our article. This research is an important step to disentangling the neuropathologic underpinnings of CI after TBI, and we are excited about the inroads being made into this rapidly evolving field.