Diagnostic value of CSF biomarker profile in frontotemporal lobar degeneration

Background: Cerebrospinal fluid (CSF) biomarkers have been increasingly studied in dementia clinical and differential diagnosis. Methods: We assessed levels of total tau protein (UT), tau phosphorylated at threonine 181 (tau(P-181)), and beta-amytoid(1-42) (A beta 42) in 34 patients with frontotemporal lobar degeneration (FTLD), 76 Alzheimer disease (AD) cases, and 93 controls (CTRL). Double sandwich enzyme-linked immunosorbent assays (Innogenetics) were used for measurements. Results: Total tau was significantly increased and A beta 42 decreased in FTLD and AD patients as compared with CTRL. CSF tau(P-181) levels were significantly increased only in AD. The tau(T)/A beta 42 ratio successfully discriminated FTLD from CTRL with a 86.7% specificity and 80.6% sensitivity, whereas the tau(T) alone was more specific (95.7%) but less sensitive (64.75%). For the discrimination of FTLD from AD, tau(T)/A beta 42 ratio was better (90.3% sensitivity and 64.5% specificity) compared with the other biomarkers alone or in combination, whereas tau(P-181) was less sensitive but more specific (68.4% and 85.7%, respectively). Subtype analysis revealed that the most AD-like profile of biomarkers were observed in FTLD with motor neuron signs, whereas the most non-AD profile were observed in patients with primary progressive aphasia. Conclusions: Combined analysis of CSF biomarkers may be useful for the best possible antemortem discrimination of FTLD from AD.