Examining Alzheimer’s Disease Blood‐Based Biomarkers and Cognition Among Non‐Hispanic White and Mexican Americans After Traumatic Brain Injury

Abstract

AbstractBackgroundThere is limited evidence on the relationship of traumatic brain injury with loss of consciousness (TBI‐LOC) and Alzheimer’s disease (AD) blood‐based biomarkers in relation to cognition. This research has predominantly examined associations among non‐Hispanic White (NHW) male service members and veterans, which limits generalizability to ethnically diverse community‐dwelling individuals. This study evaluated cognition in relation to TBI‐LOC in a NHW and Mexican American (MA) sample from Dallas‐Fort Worth, Texas in the United States.MethodData were obtained from the Health and Aging Brain Study – Health Disparities. Excluding participants with failed performance validity testing, evidence of alcohol use disorder, severe anxiety/depression, and a history of stroke or seizures, we estimated a cognitive composite using principal component analysis of the cognitive test battery. The remaining sample (n = 899) enabled baseline comparison of those with and without TBI‐LOC, before examining cognition within the TBI‐LOC group (n = 134, mean age(range) = 66.69±7.10(50‐87), mean education = 12.96±4.74, 41% female, 24.6% MA Spanish‐speaking). Multiple regression model comparisons explained variance in cognition by sociodemographic factors (age, gender, education, ethnicity/language), AD blood‐based biomarkers (Aβ42/Aβ40, Tau, Neurofilament light), and TBI‐LOC variables. TBI‐LOC variables included TBIs with loss of consciousness >30 minutes, age at first TBI‐LOC, and longest period of unconsciousness after TBI, scored by the Ohio State University TBI Identification Method.ResultThe TBI‐LOC group did not differ from the non‐TBI‐LOC group across age, education, ethnicity/language, CDR status, or cognition (ps > 0.05); they did differ by gender where the TBI‐LOC group was 59% male compared to 42.4% in the non‐TBI‐LOC group (p <0.001). Within the TBI‐LOC group, sociodemographic factors explained 49.6% of variance in cognition, and the inclusion of AD biomarkers accounted for an additional 0.4% of variance (p = 0.241). The final model including the TBI‐LOC variables explained an additional 2.5% of variance (p = 0.038) in cognition.ConclusionCognitive differences between participants with and without history of TBI‐LOC were not demonstrated. Among those with TBI‐LOC, higher severity of injury was associated with lower cognition, while AD blood‐based biomarkers had non‐significant associations with cognition. Further investigation of alternative biomarkers and specific cognitive domains among ethnically diverse individuals with TBI is warranted.