Clinical usefulness of cerebrospinal fluid biomarkers in Alzheimer's disease.

Background: Alzheimer's disease (AD) is a complex disease that shares clinical features with other dementias. It is important to establish a specific and reliable diagnosis. Nowadays, AD diagnosis is based on cerebrospinal fluid (CSF) biomarkers. However, the corresponding cut‐offs differ amongst studies. This study aims to evaluate the CSF biomarkers in the AD differential diagnosis. Methods: Clinical relevant biomarkers (amyloid β42 (Aβ42), t‐Tau, p‐Tau, amyloid β40 (Aβ40), neurofilament light chain (NfL)) were determined in CSF samples from participants classified as AD (n = 124) and non‐AD (n = 148) patients from the Neurology Unit. They were included and evaluated consecutively (August 2018–October 2020). The clinical utility of these biomarkers was evaluated by AUC‐ROC curves and the corresponding cut‐off points were defined. Results: The results showed satisfactory accuracy (AUC‐ROC 0.91 for Aβ42, 0.890 for t‐Tau and 0.933 for p‐Tau); whilst Aβ40 and NfL did not show good discriminatory capacity (AUC‐ROC 0.557 and 0.738, respectively). The ratios Aβ42/Aβ40 and t‐Tau/Aβ42 improved the diagnosis indices of each individual biomarker, with AUC‐ROC of 0.980 and 0.971, respectively. Also, elevated levels of NfL were found in the frontotemporal dementia group compared with the other participant groups. Conclusions: The ratio Aβ42/Aβ40 showed the highest discriminating capacity between AD and non‐AD patients and might be useful in clinical practice. Regarding NfL, it is not a specific biomarker for AD; however, it might be helpful for the differential diagnosis of frontotemporal dementia. Nevertheless, further analysis in an external cohort is required in order to validate these results. [ABSTRACT FROM AUTHOR]