Single molecule array (Simoa) ultrasensitive immunoassays provide a highly sensitive and specific method of quantifying AD biomarkers in the plasma.6 11 Several AD biomarkers have shown promise and include the amyloid beta (Aβ) species12 13 and τ species (both phosphorylated τ (p-tau) and total τ (t-tau)).6 14 15. Here, MAPT is linked to Alzheimer disease.