Inflammatory markers in AD and MCI patients with different biomarker profiles

ObjectiveThe 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.MethodsIL-6, ACT, CRP, Aβ42, 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 Aβ42/tau risk profile.ResultsCSF and serum CRP levels were significantly higher in MCI compared to AD patients after adjustment for age, ApoE ɛ4 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.ConclusionsThese findings suggest that inflammatory processes might be involved in early stages of AD, even before Aβ and tau changes are present in CSF of MCI patients.