Plasma Alzheimer's biomarkers and brain amyloid in Hispanic and non-Hispanic older adults

INTRODUCTION: Alzheimer's disease studies often lack ethnic diversity. METHODS: We evaluated associations between plasma biomarkers commonly studied in Alzheimer's (p-tau181, GFAP, and NfL), clinical diagnosis (clinically normal, amnestic MCI, amnestic dementia, or non-amnestic MCI/dementia), and A ss-PET inHispanic and non-Hispanic older adults. Hispanics were predominantly of Cuban or South American ancestry. RESULTS: Three-hundred seventy nine participants underwent blood draw(71.9 +/- 7.8 years old, 60.2% female, 57% Hispanic of which 88% were Cuban or South American) and 240 completed A ss-PET. P-tau181 was higher in amnestic MCI (p= 0.004, d= 0.53) and dementia (p < 0.001, d = 0.97) than in clinically normal participants and discriminated A ss-PET[+] andA ss-PET[-] (AUC = 0.86). P-tau181 outperformed GFAP and NfL. There were no significant interactions with ethnicity. Among amnestic MCI, Hispanics had lower odds of elevated p-tau181 than non-Hispanic (OR = 0.41, p = 0.006). DISCUSSION: Plasma p-tau181 informs etiological diagnosis of cognitively impaired Hispanic and non-Hispanic older adults. Hispanic ethnicity may relate to greater likelihood of non-Alzheimer's contributions to memory loss.