The Large Effect Size of Urinary Total Antioxidant Capacity in Behavioral Symptoms of Young Autistic Individuals: Comparion with Omega-3 Fatty Acid and Superoxide Dismutase in Plasma

Abstract

Objective: The imbalance between increased oxidative stress and reduced antioxidant defense has been implicated in the pathophysiology of autism spectrum disorders (ASD). Which of these has a greater impact on ASD behavioral symptoms is still unclear. We measured urinary levels of the oxidative stress biomarker hexanoyl-lysine (HEL), the total antioxidant capacity (TAC) and the DNA methylation biomarker 8-hydroxy-2′-deoxyguanosine (8- OHdG) and their relation to the plasma levels of the oxidative stress biomarker superoxide dismutase (SOD) and of the anti-inflammatory fatty acid eicosapentaenoic acid (EPA). Methods: We studied the relationships between these biomarkers and behavioral symptoms in 19 individuals with ASD (mean age 10.9 ± 5.3 years) and 11 healthy controls (mean age 14.3 ± 6.3 years). Behavioral symptoms were evaluated using the Aberrant Behavior Checklist (ABC). Results: Ages were not significant difference between two groups. The ASD group showed significantly reduced levels of urinary TAC and significantly increased levels of urinary HEL compared to the control group. Urinary 8- OHdG levels or plasma SOD and EPA levels were not significantly different between the two groups. The ABC subscale and total scores were significantly higher in the ASD group had significantly higher ABC subscale and total scores than he control group. Stepwise regression analysis and the standardized regression coefficient indicated that urinary TAC levels provided greater impact for distinguishing the two groups. There was significant correlation between the urinary TAC levels and plasma EPA levels and the ABC irritability scores. Conclusion: Urinary TAP levels may be important in the imbalance between the urinary levels of HEL and TAC, and altered plasma SOD levels may contribute to this imbalance.