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

• Main Authors: Cecilia Marelli, Laure‐Anne Gutierrez, Nicolas Menjot de Champfleur, Celine Charroud, Delphine De Verbizier, Jacques Touchon, Patrice Douillet, Claudine Berr, Sylvain Lehmann, Audrey Gabelle
• Format: Article
• Language: English
• Published: Wiley 2015-09-01
• Series: Alzheimer’s & Dementia: Diagnosis, Assessment & Disease Monitoring
• Subjects: Alzheimer's disease; Frontotemporal lobar degeneration; Late‐onset frontotemporal lobar degeneration; Cerebrospinal fluid; Biomarkers; Differential diagnosis
• Online Access: https://doi.org/10.1016/j.dadm.2015.06.004
• ISSN: 2352-8729

Abstract 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, bvFTLD/FTLD), whereas the AD patients were either in the AD (>1.06, AD/AD) or in the FTLD range (<1.06, AD/FTLD); CSF biomarkers were significantly different in these three groups, but not neuroradiological features or presence of episodic memory deficit. Discussion Late‐onset bvFTLD is underdiagnosed. The available CSF biomarker ratio cutoff need further improvement and overestimated late‐onset bvFTLD but could potentially differentiate it from AD, notably in case of conflicting results.