Medical comorbidities and ethnicity impact plasma Alzheimer's disease biomarkers: Important considerations for clinical trials and practice.

Introduction: Despite the clinical implementation, there remain significant gaps in our knowledge regarding the impact of race/ethnicity or common medical comorbidity on plasma Alzheimer's disease (AD) biomarkers.

Methods: Plasma biomarkers of amyloid beta (Aβ) Aβ , total tau, and neurofilament light chain (NfL) were measured across cognitively normal Mexican Americans (n = 445) and non-Hispanic Whites (n = 520).

Results: Dyslipidemia was associated with elevated Aβ (P = .01) and Aβ (P = .001) while hypertension was associated with elevated Aβ (P = .003), Aβ (P < .001), and total tau (P = .002) levels. Diabetes was associated with higher Aβ (P < .001), Aβ (P < .001), total tau (P < .001), and NfL (P < .001) levels. Chronic kidney disease (CKD) was associated with elevations in Aβ (P < .001), Aβ (P < .001), total tau (P < .001), and NfL (P < .001) levels. Mexican Americans had significantly lower Aβ (P < .001) and higher total tau (P = .005) levels.

Discussion: Plasma AD biomarkers vary significantly in association with common medical comorbidities as well as ethnicity. These findings are important for those using these biomarkers in clinical practice and clinical trials.