Cerebrospinal fluid Aβ40 is similarly reduced in patients with Frontotemporal Lobar Degeneration and Alzheimer's Disease

Cerebrospinal fluid (CSF) biomarkers have been increasingly studied for dementia diagnosis, however the accuracy to distinguish between different forms of dementia is still unsatisfactory. In this study, the added value of another CSF AD-peptide (A beta 40), along with the core CSF markers t-Tau, p-Tau, and A beta 42, in the discrimination between two large dementia groups of Frontotemporal Lobar Degeneration (FTLD; n = 107), Alzheimer's Disease (AD; n = 107) and non-demented subjects (n = 33) was evaluated. In FTLD, t-Tau and p-Tau were significantly increased in relation to controls, but lower than in AD, while A beta 42 was similar in FTLD and controls, but higher than in AD. Equally reduced A beta 40 levels were seen in both dementia groups, and therefore the combination of A beta 40 with core CSF biomarkers optimally discriminated FTLD and AD patients from controls. A beta 42 and t-Tau were selected as the best biomarker subset to differentiate FTLD from AD, with no added value of A beta 40 to the model. Diagnostic accuracy between FTLD and AD was still sub-optimal, with a significant percentage (23%) of FTLD patients, in particularly women, carrying an ApoE-epsilon 4 allele, showing a CSF-AD biomarkers profile. Although CSF A beta 40 does not appear to have an additional value in the distinction between FTLD and AD, it increases the discrimination between subjects with dementia from controls. A CSF-AD biomarker profile can be seen in patients with a clinical phenotype of FTLD, reinforcing the need for autopsy confirmation. (C) 2015 Elsevier B.V. All rights reserved.