Inflammatory markers in AD and MCI patients with different biomarker profiles

Objective: The aim of this study was to demonstrate the involvement of the inflammatory proteins IL-6, ACT and CRP early in the pathology process of AD in patients with mild cognitive impairment (MCI) and AD. Methods: IL-6, ACT, CRP, A beta 42, phospho-tau (p-tau) and total tau concentrations in serum and CSF of 145 patients with probable AD and 67 patients with MCI were measured by sandwich ELISA. MCI patients were characterized as high-respectively low-risk MCI according to their A beta 42/tau risk profile. Results: CSF and serum CRP levels were significantly higher in MCI compared to AD patients after adjustment for age, ApoE epsilon 4 genotype and cardiovascular diseases (p<0.01). This difference remained present in patients with a low-risk biomarker profile for AD after adjustment for abovementioned covariates. CSF IL-6 levels were also significantly higher in MCI patients with a low-risk CSF profile. Conclusions: These findings suggest that inflammatory processes might be involved in early stages of AD, even before A beta and tau changes are present in CSF of MCI patients. (C) 2008 Elsevier Inc. All rights reserved.