title: Potential biomarkers relating pathological proteins, neuroinflammatory factors and free radicals in PD patients with cognitive impairment: a cross-sectional study.
abstract: BACKGROUND
  Cognitive impairment strikingly reduces the quality of life of Parkinson's disease (PD) patients. Studies find that pathological proteins, neuroinflammatory factors and free radicals may involve in the pathogenesis of cognitive impairment of PD, however, results are inconclusive.
  
  
  METHODS
  We recruited 62 PD patients and 31 healthy controls. PD patients were identified with cognitive impairment, including PD with mild cognitive impairment (PD-MCI) and PD with dementia (PDD) according to the diagnostic criteria for PD-MCI and PDD issued by Movement Disorder Society Task Force. The levels of pathological proteins, including β-amyloid 1-42 (Aβ1-42),Total-tau (T-tau) and phosphorelated tau (P-tau), neuroinflammatory factors,including tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6), interferon-γ (INF-γ) and prostaglandin E2 (PGE2), free radicals, including hydroxyl radical (·OH), hydrogen peroxide (H2O2) and nitric oxide (NO) in cerebrospinal fluid(CSF) were detected. The levels of above factors in CSF were compared among healthy controls and patients with and without cognitive impairment. Correlation analyses were performed between Montreal Cognitive Assessment (MoCA) score and the levels of above factors in CSF.
  
  
  RESULTS
  T-tau level in CSF from PD-CI patients are significantly elevated comparing with those without cognitive impairment and controls (P = 0.016 and 0.004, respectively). The levels of P-tau (S396) and · OH in PD-CI patients are significantly higher than controls (P = 0.001 and 0.014, respectively). IL-6 levels in PD-CI patients are strikingly enhanced comparing with those without cognitive impairment (P = 0.005). MoCA score is negatively correlated with the levels of T-tau (r = -0.340), P-tau (S396) (r = -0.448), IL-6 (r = -0.489) and · OH (r = -0.504) in PD-CI patients.
  
  
  CONCLUSIONS
  Elevated levels of T-tau, P-tau (S396), IL-6 and · OH in CSF are significantly correlated with cognitive impairment in PD patients. This investigation may suggest the potential biomarkers relating pathological proteins, neuroinflammatory factors and free radicals in PD patients with cognitive impairment.
authors.forename: Shu-Yang
authors.initials: SY
authors.lastname: Yu
authors.forename: Li-Jun
authors.initials: LJ
authors.lastname: Zuo
authors.forename: Fang
authors.initials: F
authors.lastname: Wang
authors.forename: Ze-Jie
authors.initials: ZJ
authors.lastname: Chen
authors.forename: Yang
authors.initials: Y
authors.lastname: Hu
authors.forename: Ya-Jie
authors.initials: YJ
authors.lastname: Wang
authors.forename: Xiao-Min
authors.initials: XM
authors.lastname: Wang
authors.affiliation: Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing 100050, China. ttyyzw@163.com.
authors.forename: Wei
authors.initials: W
authors.lastname: Zhang
mesh_terms: D000368:Aged; D015415:Biomarkers / Q000134:cerebrospinal fluid*; D003072:Cognition Disorders / Q000134:cerebrospinal fluid* / Q000209:etiology; D003430:Cross-Sectional Studies; D005260:Female; D005609:Free Radicals / Q000134:cerebrospinal fluid*; D006801:Humans; D018836:Inflammation Mediators / Q000134:cerebrospinal fluid*; D008297:Male; D008875:Middle Aged; D009419:Nerve Tissue Proteins / Q000134:cerebrospinal fluid*; D010300:Parkinson Disease / Q000134:cerebrospinal fluid* / Q000150:complications
chemical_list: D015415:Biomarkers; D005609:Free Radicals; D018836:Inflammation Mediators; D009419:Nerve Tissue Proteins