Study on oxidative stress and inflammatory/antioxidant substance levels in autism spectrum disorder

The etiology of autism spectrum disorder (ASD) includes oxidative stress and brain inflammation. We investigated the relationship among oxidative stress markers, in vivo inflammatory substances, and antioxidants that can be easily measured in the clinic and compared them between children with ASD and those with typical development (TD).

Sixty-one children with TD and 199 with untreated ASD were investigated. They were Japanese children aged 2-15 years and were divided into those aged <7 and ≥7 years. Serum levels of reactive oxygen metabolites (ROMs), high-sensitivity C-reactive protein (hsCRP), prolactin (PRL), albumin (Alb), total bilirubin (T-Bil), and uric acid (UA) were measured. These measurements were compared between TD and ASD, and the relationship between oxidative stress and relevant laboratory parameters was analyzed.

The hsCRP and PRL levels were significantly higher in patients with ASD than in those with TD. Among those aged <7 years, hsCRP and PRL were significantly higher in those with ASD than in those with TD. Among those aged ≥7 years, ROMs, hsCRP, and PRL were significantly higher in those with ASD than in those with TD. In ASD, ROMs were significantly correlated with hsCRP, Alb, T-Bil, and PRL. In contrast, no significant correlations were found in the TD group except for the relationship between ROMs and hsCRP in those aged <7 years.

The results suggest that serum levels of in vivo inflammatory substances, stress-related substances, and antioxidants are altered in ASD under oxidative stress.