Diagnostic Value of CSF Biomarker Profile in Frontotemporal Lobar Degeneration

Abstract

Cerebrospinal fluid (CSF) biomarkers have been increasingly studied in dementia clinical and differential diagnosis. We assessed levels of total tau protein (tauT), tau phosphorylated at threonine 181 (tau P-181), and beta-amyloid1-42 (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. 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 tauT/A beta 42 ratio successfully discriminated FTLD from CTRL with a 86.7% specificity and 80.6% sensitivity, whereas the tauT alone was more specific (95.7%) but less sensitive (64.75%). For the discrimination of FTLD from AD, tauT/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. Combined analysis of CSF biomarkers may be useful for the best possible antemortem discrimination of FTLD from AD.