A HABLE study of the relationship of blood‐based biomarkers of AD and cognition functioning in the cognitively normal: The impact of ethnicity. (31st December 2021) - Hall, James R.
Abstract: Background: Blood‐based biomarkers of amyloid accumulation (Abeta40, Abeta 42), markers of neurodegeneration (NfL) and markers of neuronal injury (Tau) have all been proposed as biomarkers of early brain changes linked to the development of cognitive impairment and Alzheimer's disease. The impact of ethnic differences on this relationship has received little attention. The current study examined the relationship of these blood‐based biomarkers to performance on cognitive tests in cognitively normal older Mexican Americans (MA) and Non‐Hispanic Whites (NHW) to assess the impact of ethnicity. Method: Cognitively normal participants were drawn from a community‐based, longitudinal study of cognitive aging in MAs. 647 MAs (447 females, 200 males) and 644 NHWs (372 females, 272 males) were administered a neuropsychological battery to assess current level of cognitive functioning. Levels of plasma total tau, Abeta 40, Abeta 42and NfL were assayed via Single Molecule Array (Simoa) technology. Data were analyzed using t tests and linear regression. Result: MAs were significantly younger and had significantly fewer years of education than NHWs. MAs had higher levels of Abeta 40, Abeta 42 and NfL and lower levels of total tau. Regression analyses by ethnicity controlling for age and education revealed no significant relationship between any of the markers and any of the cognitive tests for MAs. Regression analyses for NHWs showed significant relationships between measures of memory, language, processing speed and Abeta 40; executive functions and NfL and attention and tau and Abeta 42. Conclusion: The results of the current research support the importance of assessing ethnic differences in the relationship of these biomarkers to cognitive functioning. It is likely that other biomarkers may be better predictors of cognitive functioning and cognitive decline for MAs. Further investigation of the nature of the relationship of specific biomarkers to specific cognitive functions in cognitively normal NHWs including neuroimaging is warranted.