The relationship between peripheral immune cell markers and cognitive functions in patients with schizophrenia

Abstract

Objectives The purpose of this study was to investigate the relationship between peripheral immune cell markers and cognitive functions in patients with schizophrenia and healthy controls. Methods Thirty-five patients diagnosed with schizophrenia with a stable course and a control group of 35 individuals matched in terms of sex, education, and age were included in this cross-sectional study. The Wisconsin Card Sorting Test (WCST), the Rey Auditory Verbal Learning Test (RAVLT), and the Stroop Test were used for neuropsychological evaluation. Blood neutrophil and lymphocyte percentages, neutrophil-lymphocyte ratio (NLR), and systemic immune-inflammation index (SII) values were calculated. Results The female patients exhibited significantly higher NLR and neutrophil percentages than the female controls and higher NLR, neutrophil percentage, and SII than the male patients. The increased neutrophil percentages and NLR and decreased lymphocyte percentages in the female patients were significantly correlated with worsening Stroop interference and RAVLT 1 scores. Additionally, a longer duration of illness was significantly correlated with elevated NLR, SII, and neutrophil percentage and a decreased lymphocyte percentage. A higher number of previous hospitalizations was correlated with elevated SII and decreased lymphocyte percentages. Regression analysis showed a significant association between neutrophil percentages and Stroop interference scores used to evaluate attentional functions in patients with schizophrenia. Conclusions These study results suggest that gender and the course of the illness may affect NLR and SII values. An elevated neutrophil percentage may be one of the factors affecting attentional dysfunction in patients with schizophrenia. Prospective studies are now needed to verify these findings.