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. Neurology Asia 2016; 21(4) : 349 – 356 Address for correspondence: Byeong C. Kim, M.D., Department of Neurology, Chonnam National University Medical School, 42 Jebong-ro, Dong-gu, Gwangju, 501-757, South Korea. Tel: +82-62-220-6123, E-mail: [email protected] INTRODUCTION Cognitive impairment is commonly associated with Parkinson’s disease (PD), and the prevalence of dementia in PD varies depending on age, disease duration, and the population surveyed. The specific cause and mechanism underlying the development of dementia in patients with PD remain unknown. Inflammation has been suggested to play an important role in the pathogenesis of PD as well as in that of Alzheimer’s disease (AD) and the cognitive impairment in general population. C-reactive protein (CRP) is synthesized in the liver and high-sensitivity CRP (hs-CRP) is a sensitive biomarker of systemic inflammation. It is associated with PD as well as cognitive decline, dementia, atherosclerosis, and cardiovascular diseases. Increased serum hs-CRP levels have been associated with poor cognitive function in the general population, and an increased risk of AD and vascular dementia. However, no association was found between hs-CRP and cognition in other studies involving older persons. Because inflammation appears to play a role in cognitive impairment and PD, we hypothesized the existence of an association between serum hs-CRP levels and cognitive function in patients with PD. This study aimed to compare the level of hs-CRP among PD patients with normal cognition, mild cognitive impairment (MCI), and dementia and to investigate the association between serum concentrations of hs-CRP and cognitive function in these patients. Neurology Asia December 2016