Neurochemical dementia diagnostics: a simple algorithm for interpretation of the CSF biomarkers

Cerebrospinal fluid (CSF)-based neurochemical dementia diagnostics (NDD) is a well-established diagnostic tool for neurodegenerative disorders, including Alzheimer's disease (AD). However, the direct comparison of the concentrations of the biomarkers between laboratories is often very misleading, due to relatively high inter-laboratory discrepancies of normal/abnormal ranges (cutoff values). Therefore, an interpretation tool might be useful for centers performing NDD to facilitate a standardized, diagnostic-oriented reporting of the data on biomarkers. In this study, we present a simple, easy-to-implement algorithm allowing diagnostic-relevant categorization of patients according to the outcome of the CSF NDD results and, correspondingly, enabling reporting of the data to clinicians in a clear and easy-to-follow form. The algorithm is flexible and cutoff values independent, meaning each laboratory can easily supplement it with the cutoff values and normal/abnormal ranges according to the needs; the only prerequisite is to perform the standard CSF NDD assays (amyloid beta peptides and Tau/pTau).