Combined assessment of tau and neuronal thread protein in Alzheimer's disease CSF

Objective: Comparative study of CSF levels of tau and AD7C-neuronal thread protein (NTP) in patients with AD and control subjects. Background: AD is c haracterized by neurofibrillary tangles composed of the abnormally hyperpho sphorylated microtubule-associated protein tau. AD7C-NTP is a proposed AD m arker expressed at early stages of neurofibrillary degeneration. Methods: E nzyme-linked immunosorbent assays specific for tau and AD7C-NTP. CSF sample s were obtained from 35 demented patients (25 with antemortem clinical diag nosis of probable AD, 5 with neuropathologic diagnosis of definite AD, 5 wi th Lewy body pathology), 29 nondemented patients with PD, and 16 elderly he althy control subjects. Receiver operating characteristics (ROC) and multiv ariate discriminant analysis for AD versus controls. Correlational analysis of CSF tau and AD7C-NTP and of each marker with Mini-Mental State Examinat ion (MMSE) scores was performed. Results: Levels of both tau and AD7C-NTP w ere significantly elevated in the AD patients compared with control subject s. ROC analysis showed that CSF tau distinguished between patients with AD and nondemented control subjects with 63% sensitivity and 89% specificity, AD7C-NTP with 70% sensitivity and 87% specificity. Combined evaluation of b oth markers with discriminant analysis raised the specificity to 93% at a 6 3% sensitivity level. Both markers positively correlated with each other wi thin the AD group, but not among control subjects. CSF levels of AD7C-NTP, but not of tau, showed a small but significant inverse correlation (r = -0. 43) with MMSE scores of AD patients, Conclusions: CSF levels of tau and AD7 C-NTP may be useful biomarkers for AD.