title: Plasma Aβ but not tau is related to brain PiB retention in early Alzheimer's disease.
abstract: Recent advances in biomarkers provide the possibility of early or preclinical diagnosis of Alzheimer's pathology. Currently, decreased levels of Aβ-42 and increased levels of tau proteins in cerebral spinal fluid are considered reliable biomarkers of Alzheimer's disease (AD); however, little evidence exists for the use of amyloid and tau protein levels in the plasma as useful biomarkers. We investigated the potential use of plasma biomarkers to diagnose AD and explored their relationships with brain Aβ deposition in amyloid imaging. We used an immunomagnetic reduction assay to measure the plasma levels of Aβ40, Aβ42, and tau proteins in 20 older control participants and 25 participants who had either mild cognitive impairment due to AD or early AD dementia. All participants received (11)C-labeled Pittsburgh compound B PET scans. The sensitivity of the plasma tau level at the cutoff value of 28.27 pg/mL was 92%, and the specificity was 100%; the sensitivity of the Aβ42/40 ratio at the cutoff value of 0.3693 was 84%, and the specificity was 100%. Regression analyses of the effects of plasma protein levels on brain amyloid retention, as determined by standard uptake value ratios in either side of the frontal, parietal, and temporal lobes and the precuneus, are predicted only by ratios of plasma Aβ42/40 (R(2) 0.326-0.449, all p < 0.001) but not by plasma tau levels. Plasma Aβ in terms of Aβ42/40 might provide an indirect estimation of Aβ deposition in the brain.
authors: Departments of Neurology, ‡Nuclear Medicine, National Taiwan University Hospital, §Institute of Brain and Mind Sciences, College of Medicine, National Taiwan University, ∥Department of Psychology, ⊥Graduate Institute of Biomedical Engineering and Bio-informatics, and #Molecular Imaging Center, National Taiwan University , Taipei 100617, Taiwan.
authors: Kai-Yuan
authors: KY
authors: Tzen
authors: Shieh-Yueh
authors: SY
authors: Yang
authors: Ta-Fu
authors: TF
authors: Chen
authors: Ting-Wen
authors: TW
authors: Cheng
authors: Herng-Er
authors: HE
authors: Horng
authors: Hsiang-Ping
authors: HP
authors: Wen
authors: Ya-Yao
authors: YY
authors: Huang
authors: Chyng-Yann
authors: CY
authors: Shiue
authors: Ming-Jang
authors: MJ
authors: Chiu
mesh_terms: D000368:Aged; D000544:Alzheimer Disease / Q000097:blood* / Q000000981:diagnostic imaging / Q000473:pathology*; D016229:Amyloid beta-Peptides / Q000097:blood*; D000814:Aniline Compounds; D052160:Benzothiazoles / Q000378:metabolism*; D001921:Brain / Q000000981:diagnostic imaging* / Q000378:metabolism; D016009:Chi-Square Distribution; D060825:Cognitive Dysfunction / Q000000981:diagnostic imaging / Q000473:pathology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D010446:Peptide Fragments / Q000097:blood*; D011569:Psychiatric Status Rating Scales; D011877:Radionuclide Imaging; D012044:Regression Analysis; D013844:Thiazoles; D016875:tau Proteins / Q000378:metabolism
chemical_list: C475519:2-(4'-(methylamino)phenyl)-6-hydroxybenzothiazole; D016229:Amyloid beta-Peptides; D000814:Aniline Compounds; D052160:Benzothiazoles; D010446:Peptide Fragments; D013844:Thiazoles; C078592:amyloid beta-protein (1-40); C075222:amyloid beta-protein (1-42); D016875:tau Proteins
keywords: 11C-PiB; AD pathology; beta amyloid; cognitive function; mild cognitive impairment; plasma biomarker; tau