Serum hs-CRP levels are increased in de novo parkinson's disease independently from age of onset

Background: Microglia in the brain are the counterpart of macrophages and it functions as a first defense in the brain. The double-edged feature of microglia has explained that the inflammatory state of microglia in aged brains induces them to over-respond to small stimuli that are otherwise well controlled in young brains. The clinical effect of microglia in patients with Parkinson's disease (PD) is poorly defined. This prospective study assessed the peripheral concentrations of hs-CRP, a protein able to reflect neuroinflammation in the CNS, in de novo PD patients with varying ages of onset. Methods: We examined 435 patients with de novo PD and 221 healthy subjects and the differences in hs-CRP between these groups were investigated. The PD group was classified into 4 subgroups according to the age of de novo PD to investigate the relationship between hs-CRP and the aging process in de novo PD. Results: There were significantly higher serum hs-CRP levels in patients with PD compared with healthy subjects. A post-hoc analysis of the 4 PD subgroups showed no significant differences in serum hs-CRP level. Conclusion: We assumed that neuroinflammatory reactions play a role in the pathogenesis of PD, but found no clinical evidence of a neuroprotective effect against PD in young brains. To clarify the role of microglia and aging in the pathogenesis of PD, future longitudinal studies involving a large cohort are required.