ASSOCIATION OF PLASMA AMMONIA WITH BEHAVIORAL SEVERITY IN AUTISM SPECTRUM DISORDER

Abstract

Background: Autism spectrum disorder (ASD) is a complex neurodevelopmental condition characterized by persistent deficits in communication, social interaction, and behavior. While its behavioral features are well documented, the biochemical correlates of symptom severity remain underexplored. Plasma ammonia, a neurotoxic metabolite, may contribute to ASD pathophysiology by disrupting neuronal signaling and brain metabolism. Objectives: This study aimed to measure plasma ammonia levels in children diagnosed with ASD and to evaluate the association between ammonia concentration and the severity of autistic behaviors using the Childhood Autism Rating Scale (CARS). Methods: A cross-sectional observational study was conducted over 10 months at a tertiary pediatric institution in Kerala, India. Fifty-three children aged 3–7 years with a confirmed diagnosis of ASD (DSM-5 criteria) were retrospectively analyzed. Plasma ammonia concentrations were measured using the Beckman Coulter AU680 analyzer, and behavioral severity was assessed using CARS. Pearson correlation analysis was used to determine associations between variables. Results: Plasma ammonia levels were elevated in 27 of 53 children (50.9%). A moderate, statistically significant positive correlation was observed between plasma ammonia levels and CARS scores (r = 0.31, p = 0.024). Ammonia levels did not show significant associations with age or gender. Conclusion: Elevated plasma ammonia levels may serve as a simple, low-cost, and accessible biochemical marker of behavioral severity in children with ASD. These findings support the integration of metabolic screening with behavioral assessment to facilitate early detection and personalized intervention strategies.