Study on ASD, ADHD, and Plasticizers

Several studies report 50 to 70% of individuals with autism spectrum disorder (ASD) also present with attention deficit hyperactivity disorder (ADHD). From a clinical perspective, this high rate of comorbidity is intriguing. Is ADHD in fact always present in such cases? Do environmental factors trigger these neurological disorders?

A new study in PLOS ONE focused on two compounds, the Bisphenol-A (BPA) and Diethylhexyl Phthalate (DEHP). The major pathway for BPA and DEHP excretion is via glucuronidation. Glucuronidation makes insoluble substances more water-soluble allowing for their subsequent elimination in urine.

Few reports state detoxification of these two plasticizers is compromised in children with ASD and ADHD. Consequently, their tissues are more exposed to these two plasticizers, hence T. Peter Stein and team evaluated the consequences of retaining these two plasticizers and found that though ASD and ADHD are clinically and metabolically different both share a reduction in the efficiency of detoxification for BPA and DEHP with the reductions for BPA being statistically significant.

Investigators measured the efficiency of glucuronidation in three groups of children, 66 ASD, 46 with ADHD and 37 healthy controls. The children were recruited from the clinics of Rutgers-NJ Medical School. A urine specimen was collected from each child. Multiple mass spectrometric analyses including the complete metabolome were determined and used to derive values for the efficiency of glucuronidation for 12 varied glucuronidation pathways including those for BPA and MEHP.

Key Findings of the Study

• Both fold differences and metabolome analyses showed that the three groups of children were metabolically different from each other.
• Of the 12 pathways examined, only the BPA and DEHP pathways discriminated between the three groups.
• Glucuronidation efficiencies for BPA were reduced by 11% for ASD (p = 0.020) and 17% for ADHD (p < 0.001) compared to controls. DEHP showed similar, but not significant trends.

Researchers concluded that “ASD and ADHD are clinically and metabolically different but share a reduction in the efficiency of detoxification for both BPA and DEHP with the reductions for BPA being statistically significant.”

Reference: Stein TP, Schluter MD, Steer RA, Ming X (2023) Bisphenol-A and phthalate metabolism in children with neurodevelopmental disorders. PLOS ONE 18(9): e0289841. https://doi.org/10.1371/journal.pone.0289841.