Over the course of the last 20 years, cerebrospinal fluid (CSF) biomarkers for Alzheimer's disease (AD), including amyloid beta peptide with 42 amino acids (Aβ42), total tau protein (τT), and tau protein phosphorylated at a threonine residue at position 181 (τP-181), have become a useful tool for the recognition and diagnosis of AD, even in early or atypical clinical presentations and in the presymptomatic stage of the disease [...].