CSF Biomarkers for Alzheimer’s Disease: Levels of β-Amyloid, Tau, Phosphorylated Tau Relate to Clinical Symptoms and Survival

Cerebrospinal fluid (CSF) samples from 21 patients with a clinical diagnosis of Alzheimer’s disease (AD) participating in a 5-year treatment study with the choline esterase inhibitor tacrin were retrospectively analyzed for the contents of β-amyloid (Aβ42), total tau (T-tau) and phosphorylated tau (P-tau). A significant positive correlation between the level of P-tau and the number of symptoms according to the DSM-IV criteria (p = 0.041) and the NINCDS-ADRDA (p = 0.029) was observed (i.e. higher levels were found in cases with more symptoms). A significant positive correlation between T-tau, P-tau and ADAS-cog score was identified (i.e. higher levels were found with more severe cognitive dysfunction). Patients who died during the 5-year follow-up had significantly lower levels of Aβ42 (p = 0.011) than those who were still alive. Patients who had died in a 6-year follow-up had significantly lower levels of Aβ42 (p = 0.034) and higher levels of T-tau (p = 0.041) than patients still alive. Conclusion: CSF biomarkers do aid the clinical diagnosis of AD. Increased levels of P-tau and T-tau are possible markers for severity and abundance of symptoms in AD. Low levels of Aβ42 may indicate a higher risk of early death in AD.