title: The normal equilibrium between CSF and plasma amyloid beta levels is disrupted in Alzheimer's disease.
abstract: Amyloid-beta (Abeta) with 40 (Abeta40) and 42 (Abeta42) amino acids, the main components of amyloid plaques in the Alzheimer's disease (AD) brain, can be measured in human cerebrospinal fluid (CSF) and plasma. Whereas CSF Abeta42 is decreased in AD, some studies have reported changed plasma Abeta levels in AD and in subjects with mild cognitive impairment (MCI). To this date it is unclear if and how CSF and plasma levels of Abeta correlate with each other in healthy individuals, albeit earlier studies on AD patients found no correlation between CSF and plasma Abeta. We have measured Abeta40 and Abeta42 in paired CSF and plasma samples from patients with AD (n=39), MCI (n=29) and healthy control subjects (n=18). We observed a clear correlation between CSF and plasma levels for both Abeta40 and Abeta42 in healthy individuals, whereas no such correlation could be seen for AD or MCI cases. Similarly to other studies we also found low levels of Abeta42 in AD CSF, whereas there were no significant differences in plasma Abeta levels between the diagnostic groups. Our findings suggest that the normal equilibrium between CSF and plasma Abeta may be disrupted with the initiation of amyloid deposition in the brain.
authors.affiliation: Department of Public Health/Geriatrics, Uppsala University, Uppsala, Sweden. vilmantas.giedraitis@pubcare.uu.se
authors.forename: Vilmantas
authors.initials: V
authors.lastname: Giedraitis
authors.forename: Johan
authors.initials: J
authors.lastname: Sundelöf
authors.forename: Michael C
authors.initials: MC
authors.lastname: Irizarry
authors.forename: Nina
authors.initials: N
authors.lastname: Gårevik
authors.forename: Bradley T
authors.initials: BT
authors.lastname: Hyman
authors.forename: Lars-Olof
authors.initials: LO
authors.lastname: Wahlund
authors.forename: Martin
authors.initials: M
authors.lastname: Ingelsson
authors.forename: Lars
authors.initials: L
authors.lastname: Lannfelt
mesh_terms: D000368:Aged; D000544:Alzheimer Disease / Q000097:blood* / Q000134:cerebrospinal fluid* / Q000235:genetics; D016229:Amyloid beta-Peptides / Q000097:blood* / Q000134:cerebrospinal fluid*; D053327:Apolipoprotein E4 / Q000235:genetics; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010446:Peptide Fragments / Q000097:blood* / Q000134:cerebrospinal fluid*; D012189:Retrospective Studies; D018709:Statistics, Nonparametric
chemical_list: D016229:Amyloid beta-Peptides; D053327:Apolipoprotein E4; D010446:Peptide Fragments; C078592:amyloid beta-protein (1-40); C075222:amyloid beta-protein (1-42)