Cerebrospinal fluid biomarkers and cognitive status in differential diagnosis of frontotemporal dementia and Alzheimer's disease

Objective This study aimed to determine the most appropriate cognitive and cerebrospinal fluid (CSF) biomarker setting to distinguish frontotemporal dementia (FTD) from Alzheimer's disease (AD). Method Patients with FTD, those with AD, and those without dementia were enrolled in this study. CSF amyloid-ss 42 (A ss 42), total (t)-tau, and phosphorylated (p)-tau concentrations were determined by enzyme-linked immunosorbent assays. Cognition was evaluated by the Mini-Mental State Examination (MMSE) and its domain scores. The associations of CSF biomarkers with cognitive measures were examined using regression models and the diagnostic value of CSF biomarkers was determined by receiver operating characteristics curves. Results CSF A ss 42 levels were lower, whereas t-tau/A ss 42 and p-tau/A ss 42 ratios were higher in patients with AD compared with those with FTD. Some MMSE domain scores were different in FTD and AD, but they did not improve the ability to distinguish between the two pathologies. Poor temporal orientation scores were associated with low A ss 42 levels only in patients with FTD. The p-tau/A ss 42 ratio reached sufficient levels of sensitivity and specificity to discriminate FTD with primary progressive aphasia from AD. Conclusions The ratio of CSF p-tau/A ss 42 is a sensitive and specific biomarker for discriminating patients with primary progressive aphasia from those with AD.