Soluble amyloid precursor proteins in the cerebrospinal fluid as novel potential biomarkers of Alzheimer's disease: a multicenter study

In this report, we present the results of a multicenter study to test analytic and diagnostic performance of soluble forms of amyloid precursor proteins a and b (sAPPa and sAPPb) 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 examinationX20 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 amyloidb peptides, Tau and phospho-Tau. sAPPa and sAPPb were measured with multiplexing method based on electrochemiluminescence. sAPPa and sAPPb CSF concentrations correlated with each other with very high correlation ratio (R=0.96, P<0.001). We observed highly significantly increased sAPPa and sAPPb CSF concentrations in patients with NDD characteristic for Alzheimer’s disease (AD) compared to those with NDD negative results. sAPPa and sAPPb highly significantly separated patients with AD, whose diagnosis was supported by NDD findings (sAPPa: cutoff, 117.4ngml � 1 , sensitivity, 68%, specificity, 85%, P<0.001; sAPPb: cutoff, 181.8ngml � 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 sAPPa and sAPPb might be regarded as novel promising biomarkers supporting the clinical diagnosis of AD. Molecular Psychiatry (2010) 15, 138–145; doi:10.1038/mp.2008.84; published online 29 July 2008