Increased levels of CSF phosphorylated tau in apolipoprotein E ε4 carriers with mild cognitive impairment

We investigated the correlation between the apolipoprotein E epsilon 4 allele (apoE epsilon 4) carrier status, a major risk factor of Alzheimer's disease (AD), and levels of tau protein phosphorylated at threonine 231 (P-tau(231P)) in cerebrospinal fluid (CSF) in predementia and clinical stages of AD and healthy controls (HC). Thirty-one subjects with mild cognitive impairment (MCI) who had converted to AD during follow-up were included, as well as 71 AD patients, and 29 HC subjects. In MCI, but not in AD and HC, CSF P-tau(231P) levels were significantly higher in apoE epsilon 4 carriers compared to non-carriers (p < 0.001). Controlling for disease duration, the apoE epsilon 4 effect on P-tau(231p) remained significant. Our study indicates that the apoE epsilon 4 carrier status should be considered when CSF P-tau(231P) is evaluated as biomarker candidate of AD in MCI subjects. (C) 2005 Elsevier Ireland Ltd. All rights reserved.