Relationship between serum high-sensitivity C-reactive protein levels and cognitive function in patients with Parkinson's disease

Inflammation might be associated with cognitive impairment and be involved in the pathogenesis of Parkinson's disease (PD). High-sensitivity C-reactive protein (hs-CRP) is a sensitive biomarker of systemic inflammation. This study aimed to investigate whether serum concentrations of hs-CRP are related to cognitive function in patients with PD. Patients with PD (n = 113, Hoehn and Yahr [H-Y] stage 1-4) underwent evaluation of serum hs-CRP and comprehensive neuropsychological tests that covered the cognitive domains of attention, language, visuospatial function, memory, and executive functions. We categorized subjects with PD as having normal cognition (n= 48), mild cognitive impairment (MCI) (n= 41), or dementia (n= 24). Patients with dementia had a higher hs-CRP level than patients with MCI or normal cognition (2.76 +/- 2.53 vs. 1.27 +/- 1.99 vs. 0.73 +/- 0.88 mg/L, P = 0.001). Serum hs-CRP levels were inversely associated with the Mini-Mental State Examination scores and performance on neuropsychological tests of language, visuospatial function, visual memory, and executive function. After controlling for age, sex, symptom duration, education, H-Y stage, and Unified Parkinson's Disease Rating Scale motor score, multiple regression analyses indicated statistically significant associations between hs-CRP levels and performance on neuropsychological tests of visuospatial function, visual memory, and executive function. This study suggests a possible relationship between serum hs-CRP levels and cognitive function in patients with PD, with higher levels of hs-CRP being associated with poor performance on tests of visuospatial function, visual memory, and executive function.