Peripheral inflammatory state in idiopathic normal pressure hydrocephalus patients: a cross-sectional study

Neuroinflammation may be involved in the pathogenesis of idiopathic normal pressure hydrocephalus (iNPH). However, the specific changes in the peripheral inflammatory state of patients with iNPH remain unclear.

To explore the changes in the peripheral inflammatory state of patients with iNPH and their potential value as biomarkers of clinical diagnosis and disease severity.

In this cross-sectional study, 119 iNPH patients with AD-negative pathology and 200 healthy controls (HCs) were enrolled. Clinical characteristics, including the Idiopathic Normal Pressure Hydrocephalus Grading Scale (iNPHGS), Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA), were collected along with inflammatory parameters in the peripheral blood. Logistic regression was applied to evaluate differences in peripheral inflammatory indicators, adjusting for age, sex, and comorbidities. Receiver operating characteristic (ROC) analysis was used to evaluate the diagnostic performance of the inflammatory markers. Correlations between inflammatory parameters and clinical characteristics were assessed.

Significant differences in inflammatory parameters, such as neutrophil-to-lymphocyte ratio (NLR), monocyte-to-lymphocyte ratio (MLR), and prognostic nutritional index (PNI), were observed between iNPH patients and HCs after adjusting for age, sex and comorbidities. The combination of PNI and platelet-to-high-density lipoprotein ratio (PHR) distinguished iNPH patients from HCs most significantly (area under the curve [AUC] = 0.820). Neutrophil ratio and lymphocyte ratio were associated with clinical severity and cognitive impairment of patients with iNPH.

iNPH patients exhibit an elevated peripheral inflammatory state. Peripheral inflammatory parameters, especially neutrophil ratio and lymphocyte ratio, are associated with disease severity and cognitive impairment, suggesting their potential as therapeutic targets and offering new insights into the pathophysiology of iNPH. Additionally, the inflammatory peripheral parameters may serve as valuable and convenient method in assisting clinical diagnosis.