Additionally, it is important to highlight that although some studies indicate that pre-analytical conditions can influence biomarker stability of plasma Aβ40 and plasma Aβ42, reporting significant decline after multiple freeze-thaw cycles41, 42 antother recent study has shown the relative stability of blood-based AD biomarkers, particularly amyloid and tau, at temperatures of −20 degrees for up to 15 weeks43. This evidence concerns the gene MAPT and Alzheimer disease.