Introduction
Blood‐based Alzheimer's disease (AD) biomarkers provide opportunities for community studies and across ethnic groups. We investigated blood biomarker concentrations in the Washington Heights‐Inwood Columbia Aging Project (WHICAP), a multi‐ethnic community study of aging and dementia.
Methods
We measured plasma amyloid beta (Aβ)40, Aβ42, total tau (t‐tau), phosphorylated tau (p‐tau)181, and p‐tau217, and neurofilament light chain (NfL) in 113 autopsied participants (29% with high AD neuropathological changes) and in 300 clinically evaluated individuals (42% with clinical AD). Receiver operating characteristics were used to evaluate each biomarker. We also investigated biomarkers as predictors of incident clinical AD.
Results
P‐tau181, p‐tau217, and NfL concentrations were elevated in pathologically and clinically diagnosed AD. Decreased Aβ42/Aβ40 ratio and increased p‐tau217 and p‐tau181 were associated with subsequent AD diagnosis.
Discussion
Blood‐based AD biomarker concentrations are associated with pathological and clinical diagnoses and can predict future development of clinical AD, providing evidence that they can be incorporated into multi‐ethnic, community‐based studies.
R esearch concerned with relations between literacy level and assessment of cognition among ethnically diverse elders is presented. The evidence suggests that literacy has a profound effect on neuropsychological measures across verbal and nonverbal domains, and that this effect is independent of other demographic and experiential factors such as age, years of education, sex, ethnicity, and language use. It appears that reading level is a more sensitive predictor of baseline test performance, and also that literacy skills are protective against memory decline. Adjustment for reading level, which in part reflects quality of education, overcomes the limitations of years of education as an index of educational experience among multicultural elders and thus can improve the specificity of certain neuropsychological measures. Differences in organization of visuospatial information, lack of previous exposure to stimuli, and difficulties with interpretation of the logical functions of language are possible factors that affect test performance of elders with low levels of literacy.
Within-group variation is an important yet under-studied component of cross-cultural neuropsychology. The current study explored this potential source of variation in a neurologically healthy African American elderly sample by comparing the neuropsychological test performance of nondemented groups of Caribbean-born and U.S.-born African American elders who live in New York City. Caribbean-born elders resided in the U.S. for a mean of 41.5 years (SD=17.0). Results indicate that in general, Caribbean-born elders in this cohort did not demonstrate a unique cognitive testing profile from U.S.-born African American elders. However, the Caribbean-born group demonstrated a higher quality of education than their U.S.-born counterparts. The influence of demographic factors (i.e., age and education) on neuropsychological test performance was markedly attenuated in Caribbean-born elders though reading level was the strongest predictor of test performance for all elders, regardless of birthplace.
Blood‐based phosphorylated tau (Ptau) 181 and 217 biomarkers are sensitive and specific for Alzheimer's disease. In this racial/ethnically diverse cohort study, participants were classified as biomarker positive (Ptau+) or negative (Ptau‐) based on Ptau 181 and 217 concentrations and as cognitively impaired (Sym) or unimpaired (Asym). The four groups, Ptau‐/Asym, Ptau+/Asym, Ptau‐/Sym, and Ptau+/Sym, differed by age, APOE‐4 allele frequency, total tau, neurofilament light chain, and cortical thickness measured by MRI. Our results add to increasing evidence that plasma Ptau 181 and 217 concentrations are valid Alzheimer's disease biomarkers in diverse populations.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.