Real-world diagnostic performance of blood-based biomarkers for Alzheimer’s disease: robust performance except after stroke and high charlson comorbidity index

Accurate plasma biomarker interpretation is essential for diagnosing Alzheimer’s disease (AD). This study evaluated how patient factors influence the association between plasma biomarkers and amyloid status in a memory clinic population. A cross-sectional study of 1199 participants from the Amsterdam Dementia Cohort analysed plasma biomarkers (pTau217, pTau181, Aβ 42/40 , GFAP, NfL, and a combined panel) and patient factors (comorbidities, medication use, vital signs, body mass index, and kidney function). Amyloid status was determined via amyloid PET ( n = 309) or CSF pTau181/Aβ 1−42 ( n = 890). Stroke, hypercholesterolemia, antidepressant use and Charlson Comorbidity Index (CCI) influenced biomarker performance. Stroke reduced the diagnostic value of pTau217, Aβ 42/40 and the biomarker panel, while hypercholesterolemia and antidepressant use enhanced pTau217 and Aβ 42/40 , respectively. A CCI ≥ 2 reduced the biomarker panel’s performance. Overall, patient factors had limited impact on biomarkers, but caution is needed for patients with stroke or high CCI.