Endocrine-disrupting chemicals and clinical outcomes in children with attention-deficit/hyperactivity disorder undergoing methylphenidate treatment: A 12-month follow-up study

Endocrine-disrupting chemicals (EDCs) can interfere with the endocrine system and may influence the risk of developing attention-deficit/hyperactivity disorder (ADHD). In this 12-month prospective study, we examined trends in EDC exposure and their association with neurocognitive changes in children diagnosed with ADHD. We recruited 83 children with ADHD and 80 healthy controls, measuring urinary levels of various EDCs, including mono-methyl phthalate (MMP), monoethyl phthalate (MEP), mono-n-butyl phthalate (MnBP), monobenzyl phthalate (MBzP), monoethylhexyl phthalate (MEHP), methylparaben (MP), ethylparaben (EP), propylparaben (PP), butylparaben (BP), and bisphenol-A (BPA). ADHD symptoms and cognitive performance were assessed using the ADHD-Rating Scale (ADHD-RS), Conners' Continuous Performance Test 3rd Edition (CPT3), and Conners' Continuous Auditory Test of Attention™ (CATA). At baseline, children with ADHD had significantly higher levels of MnBP and MEHP compared to healthy controls. Over the 12-month methylphenidate treatment, children with ADHD showed an increase in MEP levels and a decrease in MnBP, MEHP, MP, and BPA levels. ADHD-RS scores were negatively correlated with urinary MEP levels and positively correlated with MP levels. Additionally, CATA omission errors were positively associated with MnBP levels, while detectability errors were positively correlated with MEHP levels. These findings suggest that EDC levels in children with ADHD fluctuate during treatment and are associated with changes in ADHD symptoms and neuropsychological performance. This study provides valuable insights into the evolving relationship between EDC exposure and ADHD symptoms during treatment, contributing to the evaluation of potential health risks and informing public health policy development.