Improved discrimination of autopsy-confirmed Alzheimer's disease (AD) from non-AD dementias using CSF P-tau(181P).

To establish diagnostic accuracy (acc) and optimal cut-off levels of CSF tau phosphorylated at threonine 181 (P-tau(181P)) for discriminating Alzheimer's disease (AD) from non-AD dementias in autopsy-confirmed dementia patients, CSF levels of beta-amyloid peptide (Abeta(1-42)), total tau protein (T-tau) and P-tau(181P) from patients with definite AD (n=95) and non-AD dementias (n=50) were determined with single-parameter ELISA kits. Optimal P-tau(181P) cut-off levels for differentiating AD from pooled non-AD dementias, dementia with Lewy bodies (DLB) and frontotemporal dementia (FTD) were 50.4pg/mL (acc=0.73), 52.8pg/mL (acc=0.73) and 35.3pg/mL (acc=0.90), respectively. The optimal CSF P-tau(181P) cut-off level for discriminating AD from non-AD dementias was 50.4pg/mL. Optimal CSF P-tau(181P) cut-off levels differed between non-AD diagnostic dementia categories.