A Cross‐sectional HABS‐HD study of Plasma Biomarkers of Cognitive Decline across Diagnoses in a Diverse Community Cohort

Abstract

AbstractBackgroundDue to their low cost, less invasive nature and ready availability, plasma biomarkers of Alzheimer’s disease have been proposed as one time screening tools for clinical trials and research. The impact of ethnoracial factors on these biomarkers has received little attention. The current study investigated the levels of Aβ40, Aβ42, total tau and NfL across diagnoses for each of the three major ethnoracial groups in the US in a community based cohort of older adults.Method1862 participants (852 Mexican Americans (MA); 775 Non‐Hispanic Whites (NHW) and 235 African Americans (AA)) drawn from The Health & Aging Brain Study – Health Disparities (HABS‐HD) study were included. Diagnoses were assigned using an algorithm (decision tree) verified by consensus review. Plasma samples were assayed using Simoa technology. Data were analyzed using ANOVA comparing the level of each biomarker across the cognitive diagnoses (Normal Cognition (NC), MCI & Dementia) within each ethnoracial group co‐varying age and sex.ResultFor NHW there were no significant differences between NC, MCI and Dementia groups in levels of Aβ40 or Aβ42. For t tau, MCI t tau was significantly higher than NC. The t tau level did not differ between the two cognitively impaired groups. There was a significant effect for diagnosis for NfL with the MCI NfL and the Dementia NfL level being significantly higher than the NC NfL level. The impaired groups did not differ in NfL between the impaired groups. For the MA significant differences across diagnoses were found only for NfL. The Dementia NfL level was significantly higher than the NC and significantly higher than the MCI. The only biomarker showing significant differences across diagnoses for AA was NfL. The Dementia NfL level was significantly higher than the NC and MCI levels.ConclusionAlthough cross‐sectional, the results suggest different patterns of plasma biomarkers across diagnoses for NHW as compared to MA and AA. NfL levels were highest in the Dementia group for all. Ongoing longitudinal research will show how biomarkers change as cognition declines.