Tau protein in the diagnosis of old-age dementia

Summary the several biomarkers proposed for Alzheimerʹs disease (AD) elevated levels of tau protein have been consistently associated with AD in several clinical trials worldwide, using different tau assay systems. Although other neurodegenerative markers cannot discriminate AD from related conditions, tau is especially elevated in AD. Since abnormally phosphorylated tau is an essential component of paired helical filaments, tauʹs abnormal state may contribute to this elevation. Based upon the current phosphodependent antibodies, it is clear that tau in the cerebrospinal fluid (CSF) is phosphorylated, but is not hyperphosphorylated in AD. Tau in CSF derives from the central nervous system. Follow-up studies in AD patients show that the level of tau does not change appreciably during the course of the disease, nor does the rise in tau correlate with the degree of dementia, at least not in the more advanced stages of the disease. Recent studies indicate that tau might be an early marker, even before symptoms of dementia are evident. Furthermore, follow-up studies of patients under treatment clearly show that tau levels can be influenced during treatment, depending on the drug.