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INTRODUCTION: Commercially available plasma p-tau217 biomarker tests are not well studied in ethnically diverse samples. METHODS: We evaluated associations between ALZPath plasma p-tau217 and amyloid-beta positron emission tomography (Aß-PET) in Hispanic/Latino (88% of Cuban or South American ancestry) and non-Hispanic/Latino older adults. One- and two-cutoff ranges were derived and evaluated to assess agreement with Aß-PET. RESULTS: A total of 239 participants underwent blood draw and Aß-PET (age 70.8 ± 7.8, 55.2% female, education 15.6 ± 3.4 years, 48.9% Hispanic/Latino, 94.9% white). Plasma p-tau217 showed excellent discrimination of Aß-PET positive and negative participants (visual read: AUC = 0.91 [0.87-0.95], p < 0.001; Centiloids quantification: AUC = 0.90 [0.86-0.94]). There was a greater percent agreement between low p-tau217 and negative Aß-PET (95.8%) than high p-tau217 and positive Aß-PET (86.3%). Analyses within ethnicity-specific subgroups suggested similar p-tau217 performance. DISCUSSION: Plasma p-tau217 (ALZPath) relates to brain Aß in Hispanic/Latino and non-Hispanic/Latino older adults. Independent validation and replication are necessary to establish reference ranges and inform appropriate contexts of use across ethno-racially diverse populations. HIGHLIGHTS: Plasma p-tau217 (ALZPath) and Aß-PET were measured in Hispanic/Latino and non-Hispanic/Latino older adults.Plasma p-tau217 accurately discriminated Aß-PET positive and negative participants.Applying a two-cutoff "intermediate" plasma p-tau217 approach could reduce need for more invasive and costly testing.Plasma p-tau217 associations with Aß-PET were strong within both Hispanic/Latino and non-Hispanic/Latino groups.
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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 Aß-PET in Hispanic 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 Aß-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 Aß-PET[+] and Aß-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. HIGHLIGHTS: Alzheimer's biomarkers were measured in Hispanic and non-Hispanic older adults. Plasma p-tau181 related to amnestic cognitive decline and brain amyloid burden. AD biomarker associations did not differ between Hispanic and non-Hispanic ethnicity. Hispanic individuals may be more likely to have non-Alzheimer causes of memory loss.
