Plasma and cerebrospinal fluid levels of amyloid beta proteins 1-40 and 1-42 in Alzheimer disease.
BACKGROUND
In brains with AD, Abeta is a major component of diffuse plaques. Previous reports showed that CSF Abeta42 levels were lower in patients with AD than in controls. Although studies showed higher plasma Abeta42 levels in familial AD, a recent report has indicated that plasma Abeta42 levels were similar in a sporadic AD group and controls. However, no information is published on plasma Abeta40 and Abeta42 levels in relation to Apo E genotype or severity of dementia in sporadic AD.


OBJECTIVE
To examine plasma and cerebrospinal fluid (CSF) levels of amyloid beta protein 1-40 (Abeta40) and 1-42 (Abeta42) levels in patients with probable Alzheimer disease (AD) and elderly nondemented control subjects in relation to the apolipoprotein E (Apo E) genotype and dementia severity.


METHODS
Two university medical centers.


METHODS
Levels of Abeta40 and Abeta42 were measured in plasma from 78 patients with AD and 61 controls and in CSF from 36 patients with AD and 29 controls by means of a sandwich enzyme-linked immunosorbent assay.


RESULTS
Mean plasma Abeta40 levels were higher in the AD group than in controls (P = .005), but there was substantial overlap; Abeta42 levels were similar between the groups. Levels of Abeta40 and Abeta42 showed no association with sex or Mini-Mental State Examination scores. There was a significant relationship between age and Abeta40 level in controls but not in the AD group. Levels of Abeta40 were higher in patients with AD with the Apo E epsilon4 allele than in controls (P<.01). Cerebrospinal fluid Abeta40 levels were similar in the AD group and controls. However, Abeta42 levels were lower in the AD group than in controls (P<.001). The levels showed no association with severity of dementia.


CONCLUSIONS
Although mean plasma Abeta40 levels are elevated in sporadic AD and influenced by Apo E genotype, measurement of plasma Abeta40 levels is not useful to support the clinical diagnosis of AD. Lower levels of CSF Abeta42 in the AD group are consistent with previous studies.
Mehta
P D
PD
Department of Immunology, New York State Institute for Basic Research in Developmental Disabilities, Staten Island 10314, USA. pdmehta@worldnet.att.net
Pirttilä
T
T
Mehta
S P
SP
Sersen
E A
EA
Aisen
P S
PS
Wisniewski
H M
HM
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000097:blood* / Q000134:cerebrospinal fluid* / Q000235:genetics; D016229:Amyloid beta-Peptides / Q000097:blood* / Q000134:cerebrospinal fluid*; D053327:Apolipoprotein E4; D001057:Apolipoproteins E / Q000235:genetics; D006801:Humans; D008875:Middle Aged; D010446:Peptide Fragments / Q000097:blood* / Q000134:cerebrospinal fluid*; D011237:Predictive Value of Tests
D016229:Amyloid beta-Peptides; D053327:Apolipoprotein E4; D001057:Apolipoproteins E; D010446:Peptide Fragments; C078592:amyloid beta-protein (1-40); C075222:amyloid beta-protein (1-42)