In this report, we present the results of a multicenter study to test analytic and diagnostic performance of soluble forms of amyloid precursor proteins alpha and beta (sAPP alpha and sAPP beta) in ...the cerebrospinal fluid (CSF) of patients with different forms of dementing conditions. CSF samples were collected from 188 patients with early dementia (mini-mental state examination >or=20 in majority of cases) and mild cognitive impairment (MCI) in 12 gerontopsychiatric centers, and the clinical diagnoses were supported by neurochemical dementia diagnostic (NDD) tools: CSF amyloid beta peptides, Tau and phospho-Tau. sAPP alpha and sAPP beta were measured with multiplexing method based on electrochemiluminescence. sAPP alpha and sAPP beta CSF concentrations correlated with each other with very high correlation ratio (R=0.96, P<0.001). We observed highly significantly increased sAPP alpha and sAPP beta CSF concentrations in patients with NDD characteristic for Alzheimer's disease (AD) compared to those with NDD negative results. sAPP alpha and sAPP beta highly significantly separated patients with AD, whose diagnosis was supported by NDD findings (sAPP alpha: cutoff, 117.4 ng ml(-1), sensitivity, 68%, specificity, 85%, P<0.001; sAPP beta: cutoff, 181.8 ng ml(-1), sensitivity, 75%, specificity, 85%, P<0.001), from the patients clinically assessed as having other dementias and supported by NDD untypical for AD. We conclude sAPP alpha and sAPP beta might be regarded as novel promising biomarkers supporting the clinical diagnosis of AD.
We measured concentrations of Aβ peptides 1–42 and 1–40, and their ratio in plasma of patients carefully categorized clinically and neurochemically as having AD or other dementias with a newly ...commercially available multiplexing assay, characterized by reasonable laboratory performance (intra-assay imprecision in the range of 1.3–3.8% for Aβ1–42, and 1.8–4.1% for Aβ1–40, inter-assay imprecision for Aβ1–42, Aβ1–40, and Aβ1–42/Aβ1–40 concentration ratio in the range of 2.3–11.5%, 2.2–10.4% and 4.2–9.7%, respectively). Patients with AD or mild cognitive impairment of AD type (MCI-AD) whose clinical diagnosis was supported with CSF biomarkers (
n
=
193) had significantly lower Aβ1–42 plasma concentrations (
p
<
0.007), and Aβ1–42/1–40 ratios (
p
<
0.003) compared to patients with other dementias and MCI of other types (
n
=
64). No significant differences between persons with MCI of AD type and patients with early AD were observed, or between MCI of other types versus patients with early dementia of other types. Our findings reconfirm the hypothesis that alterations of biomarker concentrations occur early in a preclinical AD stage and that these alterations are also reflected in plasma.
We measured concentrations of A beta peptides 1-42 and 1-40, and their ratio in plasma of patients carefully categorized clinically and neurochemically as having AD or other dementias with a newly ...commercially available multiplexing assay, characterized by reasonable laboratory performance (intra-assay imprecision in the range of 1.3-3.8% for A beta 1-42, and 1.8-4.1% for A beta 1-40, inter-assay imprecision for A beta 1-42, A beta 1-40, and A beta 1-42/A beta 1-40 concentration ratio in the range of 2.3-11.5%, 2.2-10.4% and 4.2-9.7%, respectively). Patients with AD or mild cognitive impairment of AD type (MCI-AD) whose clinical diagnosis was supported with CSF biomarkers (n = 193) had significantly lower A beta 1-42 plasma concentrations (p < 0.007), and A beta 1-42/1-40 ratios (p < 0.003) compared to patients with other dementias and MCI of other types (n = 64). No significant differences between persons with MCI of AD type and patients with early AD were observed, or between MCI of other types versus patients with early dementia of other types. Our findings reconfirm the hypothesis that alterations of biomarker concentrations occur early in a preclinical AD stage and that these alterations are also reflected in plasma.
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