CSF tau proteInS In dIFFerentIal dIagnoSIS oF deMentIa

From a clinical standpoint, Alzheimer’s disease (AD) and frontotemporal lobar degeneration (FTLD) may be distinguished by a combination of clinical criteria and neuroimaging. However, in younger patients with mild cognitive deficits, it is sometimes difficult to classify patients based only on clinical findings, probably due to overlap of cognitive deficits with prominent executive and behavioral dysfunction, apraxia, and language disorders found in young AD patients [1]. Because of this overlap, it is crucially important to find new diagnostic tools to help clinicians to make an early and accurate diagnosis of a primary dementia. Previous studies on the diagnostic value of CSF total tau (t-tau) and phosphorylated tau (p-tau) proteins in differential diagnosis of early-onset AD and FTLD are variable. This is partly due to the wide range of tau protein concentrations found in postmortem brains of FTLD patients [2-4], but also due to large differences in age between the two groups [5]. To date, only few studies have evaluated CSF biomarkers between agematched AD and FTLD patients [6-8] and none evaluated CSF p-tau199. The aim of our study was to investigate the diagnostic value of total tau protein (t-tau), tau protein phosphorylated at threonine 181 (p-tau181) and tau protein phosphorylated at serine 199 (p-tau199) in agematched AD and FTLD patients.