PubMed ID: 34924380
Author(s): Schubert CR, Paulsen AJ, Pinto AA, Merten N, Cruickshanks KJ. Effect of Long-Term Storage on the Reliability of Blood Biomarkers for Alzheimer’s Disease and Neurodegeneration. J Alzheimers Dis. 2022;85(3):1021-1029. doi: 10.3233/JAD-215096. PMID 34924380
Journal: Journal Of Alzheimer’s Disease : Jad, Volume 85, Issue 3, 2022
BACKGROUND Stored blood samples from longitudinal cohort studies may be useful for studying biomarkers of preclinical Alzheimer’s disease.
OBJECTIVE This study aimed to determine the reliability of amyloid-β40 and amyloid-β42 (Aβ40, Aβ42), total tau (TTau), and neurofilament light (NfL) concentrations measured in blood samples stored long-term at -80°C.
METHODS Aβ40, Aβ42, TTau, and NfL were measured in serum and plasma samples from two longitudinal cohort studies. Serum samples had been stored at -80°C for 5 (n = 24), 14 (n = 24), and 20 years (N = 78) and plasma samples had been stored for 16 years (N = 78). Biomarker concentrations were measured in duplicate using a single molecule array assay (Simoa; Quanterix, Billerica, MA). Replicate samples for each sample type and storage length were included.
RESULTS The concentrations of Aβ40, Aβ42, TTau, and NfL were within expected ranges. Some serum TTau concentrations were below the limit of detection. The average intra-assay coefficients of variation (CV) for duplicate measures were 2-7% for all assays except for serum TTau, which were higher (CVs 13% and 17%). Mean differences in original replicate pair Aβ40, Aβ42, and NfL concentrations were slightly greater in samples stored for longer versus shorter time periods.
CONCLUSION Aβ40, Aβ42, TTau, and NfL can be measured in serum and plasma samples that have been stored up to 20 years at -80°C. Long-term storage may be associated with small increases in the variability of concentrations in samples stored 14 or more years.