Relationship between the hs-CRP as non-specific biomarker and Alzheimer's disease according to aging process

Background: Microglia are involved in immune surveillance in intact brains and become activated in response to inflammation and neurodegeneration. Microglia have different functions, neuroprotective or neurotoxic, according to aging in patients with PD. The clinical effect of microglia in patients with Alzheimer's disease (AD) is poorly defined. This prospective study was conducted to investigate the clinical effects of microglia according to the aging process in newly diagnosed AD. Methods: We examined 532 patients with newly diagnosed AD and 119 healthy controls, and the differences in hs-CRP between these groups were investigated. The patients with AD were classified into 3 subgroups according to age of newly diagnosed AD to investigate the relationship between hs-CRP and the aging process in newly diagnosed AD. Results: There was significantly higher serum high-sensitivity C-reactive protein (hs-CRP), levels in patients with AD compared with healthy controls. A post-hoc analysis of the 3 AD subgroups showed no significant differences in serum hs-CRP level between each group. Conclusion: We assumed that neuroinflammation play a role in the pathogenesis of AD, but found no clinical evidence that microglia senescence underlies the microglia switch from neuroprotective in young brains to neurotoxic in aged brains. To clarify the role of microglia and aging in the pathogenesis of AD, future longitudinal studies involving a large cohort are required.