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Assessment of Amyloid β Protein in Cerebrospinal Fluid as an Aid in the Diagnosis of Alzheimer's Disease
Author(s) -
Southwick Paula C.,
Yamagata Susan K.,
Echols Charles L.,
Higson Gail J.,
Neynaber Scott A.,
Parson Robert E.,
Munroe William A.
Publication year - 1996
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1046/j.1471-4159.1996.66010259.x
Subject(s) - cerebrospinal fluid , immunoradiometric assay , lumbar puncture , alzheimer's disease , beta (programming language) , degenerative disease , medicine , amyloid (mycology) , gastroenterology , disease , central nervous system disease , pathology , endocrinology , radioimmunoassay , computer science , programming language
The principal constituent of amyloid plaques found in the brains of individuals with Alzheimer's disease (AD) is a 39–42‐amino‐acid protein, amyloid β protein (Aβ). This study examined whether the measurement of Aβ levels in CSF has diagnostic value. There were 108 subjects enrolled in this prospective study: AD (n = 39), non‐AD controls (dementing diseases/syndromes; n = 20), and other (n = 49). CSF was obtained by lumbar puncture, and Aβ concentrations were determined using a dual monoclonal antibody immunoradiometric sandwich assay. The mean Aβ value for the AD group (15.9 ± 6.8 ng/ml) was not significantly different from that for the non‐AD control group (13.0 ± 7.1 ng/ml; p = 0.07), and substantial overlap in results were observed. Aβ values did not correlate with age ( r = −0.05, p = 0.59), severity of cognitive impairment ( r = 0.22, p = 0.21), or duration of AD symptoms ( r = 0.14, p = 0.45). These findings are in conflict with other reports in the literature; discrepant results could be due to the instability of Aβ in CSF. Aβ immunoreactivity decays rapidly under certain conditions, particularly multiple freeze/thaw cycles. Use of a stabilizing sample treatment buffer at the time of lumbar puncture allows storage of CSF without loss of Aβ reactivity. In conclusion, the total CSF Aβ level is not a useful marker for current diagnosis of AD.