Late-onset behavioral variant of frontotemporal lobar degeneration versus Alzheimer's disease: Interest of cerebrospinal fluid biomarker ratios

Introduction Cerebrospinal fluid (CSF) biomarker ratios were never evaluated in late‐onset (>65 years) behavioral variant of frontotemporal lobar degeneration (bvFTLD) versus Alzheimer's disease (AD). Methods A retrospective monocentric study on 44 clinically suspected amnestic AD or bvFTLD patients with onset after 65 years and available CSF and clinical data. Results The final clinical diagnosis was AD (n = 28; 64%), late‐onset bvFTLD (n = 14; 32%), and others (n = 2; 4%). Applying the CSF cutoff total‐tau/Aβ1–42 of 1.06, all the bvFTLD were in the FTLD range (1.06, AD/AD) or in the FTLD range (