Current application of neurochemical biomarkers in the prediction and differential diagnosis of Alzheimer’s disease and other neurodegenerative dementias

In light of the dramatically increasing prevalence of Alzheimer’s disease (AD) to be expected in the future, the development of novel therapeutics, improved differential and early diagnostics, and means for the identification of individuals at risk are urgently needed. At present, instruments for a reliable differential diagnosis in clinical dementia, mild cognitive impairment, or prodromal stages have direct practical implications for differentiating secondary dementias from neurodegenerative conditions and for treatment decisions. It may also be reasonable to enforce the incorporation of biomarkers into clinical studies as surrogate outcome parameters and as an attempt to optimize recruitment criteria. Recently, revised research criteria increasingly rely on the interpretation of biomarker patterns, including neuroimaging and CSF-based neurochemical dementia diagnosis (NDD) in supporting the clinical diagnosis. Here, we review the performance of current core CSF biomarkers (Aβ42 peptide, total tau protein and phosphorylated tau species) and try to define objectives for prospective markers, also considering blood-based tests, which would increase the acceptance and wide application of NDD. Moreover, we evaluate the role and the limitations of genotyping in the predictive diagnosis of AD.