Exposure to heavy metals and neuropsychological performance in children with and without attention deficit hyperactivity disorder (ADHD).

Heavy metal exposure can negatively impact the neuropsychological development of children and has been linked to ADHD. We investigated the association between heavy metal exposure and neuropsychological functions in children with and without ADHD. Urine samples were collected from 205 children aged 6-16 years (66 without ADHD, 139 with ADHD). Neuropsychological assessments were conducted using WISC-IV/V and CPT-2/3. Associations between Pb, Cd, Cu, As, Hg and neuropsychological outcomes were analysed using multiple linear regressions. In the overall sample, Cu was negatively associated with processing speed (β=-6.75, 95% CI:-13.42-(-0.08)), with this effect being more pronounced in ADHD children (β=-11.54 and - 12.52, 95% CI:-21.53-(-3.51)). In ADHD children, Pb (β=-11.23, 95% CI:-21.24-(-1.23)) was negatively associated with processing speed. Hg exposure was linked to CPT indicators of inattentiveness, both in overall and ADHD samples (higher detectability, commission error, omission error and slower reaction times scores). In ADHD children, Pb exposure was associated with increased commission errors (β = 5.41, 95% CI:0.89-9.39) and Cu with omission errors (β = 8.44, 95% CI:-0.02-16.89) and faster reaction time (β = 7.43, 95% CI:1.21-13.65). Our findings highlight the potentially harmful effects of Cu, Pb, and Hg on neuropsychological performance in children, with these associations being particularly pronounced among ADHD children. The findings call for public health strategies aimed at reducing environmental exposure to heavy metals in children to promote optimal neuropsychological development.