The Role of Systemic Inflammation and Haematological Parameters in Autism

Autism spectrum disorder (ASD) is a neurodevelopmental condition characterized by challenges in social communication and repetitive behaviors. Emerging evidence suggests that ASD may also involve systemic inflammatory processes. This study aimed to assess systemic inflammation in children with ASD using hematological biomarkers and to investigate the association between these markers and autism severity. A total of 75 children with ASD (mean age: 4.37±1.01 years) and 75 age- and sex-matched healthy controls (mean age: 4.41±1.06 years) were included. Complete blood count data were used to calculate neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), systemic immune-inflammation index (SII), and systemic inflammation response index (SIRI). Compared to controls, the ASD group showed significantly higher levels of leukocytes (p=0.011), neutrophils (p=0.001), monocytes (p<0.001), NLR (p=0.005), SII (p=0.001), and SIRI (p<0.001). Moreover, CARS scores, indicating autism severity, were positively correlated with these inflammatory markers (e.g., SIRI: r=0.403, p<0.001; monocyte: r=0.362, p<0.001). These findings suggest that systemic inflammation may contribute to the pathophysiology of ASD and that hematological indices could serve as accessible biomarkers for clinical evaluation.