Trace elements, cognitive function and behavioral problems in children with attention-deficit hyperactivity disorder

Environmental factors, such as trace elements and blood lead, have been implicated in the heterogeneity of children with attention deficit hyperactivity disorder (ADHD). This research aimed to investigate the relationship between blood trace elements and cognitive function as well as behavioral problems in children aged 4–12 years diagnosed with ADHD. In this study, we recruited 146 children with ADHD and 91 neurotypical controls matched for age and gender. We used atomic absorption spectrometry to measure the concentrations of Cu, Zn, Ca, Mg, Fe, and Pb in the whole blood. The Conners Parent Rating Scale (CPRS) and Wechsler intelligence tests were employed to evaluate cognitive function and behavioral problems. Compared with controls, children with ADHD exhibited higher levels of Pb. Pb levels indicated a negative correlation with the verbal comprehension index and the full intelligence scale. Cu levels indicated a negative correlation with the verbal comprehension index but positively correlated with conduct, learning, and impulsive-hyperactivity problems. In addition, Fe levels indicated a positive correlation with psychosomatic symptoms. Wechsler intelligence results indicated substantially higher scores in children with normal Zn levels than those outside the reference range. These results indicate a correlation between the present of Pb, Cu, Fe, and Zn in the blood of Chinese children with ADHD and cognitive function and behavioral problems.