Age-Dependent Correlation between Immune Parameters and Symptoms in Young Adults with Schizophrenia

Background: Schizophrenia (SCZ) is a debilitating mental disorder of unknown etiology. It is characterized by both positive and negative symptoms. Increasing evidence reports the role of immune abnormalities in the pathogenesis of SCZ. Objective: This study aimed to examine the potential effect of age on the associations between clinical symptoms and immune parameters in drug-naïve first episode SCZ (DNFES). Methods: A total of 64 young DNFES patients were recruited and divided into younger and older groups according to the median age. Immune parameters, including neutrophil (NEU), lymphocyte (LYM), and neutrophil-to-lymphocyte ratio (NLR) values, were measured and compared between the younger and older patients to investigate the potential effect of age on the correlations between immune parameters and clinical symptoms. Results: We found that NEU and NLR were significantly higher in patients compared to healthy controls, with even higher values observed in the younger group than in the older group. In addition, NEU count was correlated with clinical symptoms in older patients, while NLR was correlated with symptoms in younger patients. Linear regression analysis showed that NEU or NLR values were associated with the clinical symptoms in patients with SCZ after controlling confounders. Conclusion: Our study suggests that young adult patients had abnormal immune parameters. Furthermore, age mediated the relationships between immune parameters and symptom severity. This study provides further evidence that abnormal immune parameters, particularly an increased innate immune response, may be involved in the pathophysiology of SCZ.