Background: Many factors have been implicated in the onset of autism, including excess or deficiency in toxic or essential metals and impaired antioxidant systems. Exposure to metals is a putative risk factor for autism. Many metals can be implicated in autism as they typically disrupt enzyme functions and cell signaling processes and generate reactive oxygen species (ROS).
Patients and methods: Thirty-two autistic patients ranging in age from 2.6 to 12.7 years (mean age 5.6 years) were examined clinically. Twenty healthy children matched for age and sex were included as a control group. Serum mercury, lead, and nitric oxide were estimated in all patients.
Results: Eighteen patients presented with seizures and an epileptogenic focus in the electroencephalogram. The intelligent quotient assessment showed mental retardation in all patients: 18 had moderate retardation, two had severe retardation, and 12 had profound retardation. Assessment of the severity of autistic symptoms using the childhood autism rating scale indicated that six patients had mild, 12 had moderate, and 14 had severe autistic symptoms. The estimation of the level of mercury and lead in blood showed a significant increase compared with the control group (P=0.0001). Furthermore, nitric oxide was significantly increased compared with the control group (P=0.0001). These findings indicated a significant increase in both metal content and an imbalance in the oxidative status in the blood of autistic children.
Conclusion: Our findings suggest the hypothesis that exposure to metals and oxidative stress may be biomarkers of toxicity in autism. We recommend the consideration of supplementing autistic patients with antioxidants. We also recommend the study of introducing chelating agents for mercury and lead in patients with high toxic levels and their effect on clinical symptoms.