Differential leukocyte count is associated with clinical phenotype in Parkinson's disease

Elevated proinflammatory cytokines are associated with disease progression in patients with Parkinson's disease (PD). The aim of study is to investigate whether components of peripheral blood leukocyte are associated with clinical symptoms in patients with de novo PD.

We analyzed data from 123 newly diagnosed de novo patients who had no focal and systemic inflammatory diseases. Associations between clinical symptoms and differential leukocyte count (DLC) or DLC associated peripheral inflammatory biomarkers were examined.

Altered DLC and DLC associated peripheral inflammatory biomarkers were associated with PD related symptoms even though there was no sign of clinical inflammation. After controlling for covariables, olfaction and body mass index (BMI) were inversely associated with percentage of neutrophil, neutrophil to lymphocyte ratio, derived neutrophil to lymphocyte ratio, and positively associated with percentage of lymphocyte, lymphocyte to monocyte ratio. Patients with tremor-dominant or mixed type had lower peripheral inflammatory indices than those with akinetic rigid type.

Components of peripheral blood leukocytes reflect some clinical symptoms of PD. Patients with normosmia, tremor-dominant or mixed type, and patients without low BMI have low peripheral inflammatory indices. Relative mild peripheral inflammation may play one of major roles in developing mild disease phenotype in these patients.