Changed Plasma Levels of Zinc and Copper to Zinc Ratio and Their Possible Associations with Parent- and Teacher-Rated Symptoms in Children with Attention-Deficit Hyperactivity Disorder

Attention-deficit hyperactivity disorder (ADHD) is associated with alterations in the metabolism of some trace elements which may participate in the pathogenesis of this disorder. The aims of the present study were to investigate the trace element status (copper (Cu), zinc (Zn), copper to zinc ratio (Cu/Zn ratio), selenium (Se), and lead (Pb)) of ADHD children and compare them with the control group. Associations between examined elements and ratings of ADHD symptoms were also assessed. Fifty-eight ADHD children and 50 healthy children (aged 6-14 years) were included in the study. The concentrations of Cu, Zn, and Se in the plasma and Pb in the whole blood were measured by atomic absorption spectrometry. We found lower Zn level (p = 0.0005) and higher Cu/Zn ratio (p = 0.015) in ADHD children when compared with the control group. Copper levels in ADHD children were higher than those in the control group, but not significantly (p > 0.05). No significant differences in levels of Se and Pb between both groups were found. Zinc levels correlated with parent-rated score for inattention (r = -0.231, p = 0.029) as well as with teacher-rated score for inattention (r = -0.328, p = 0.014). Cu/Zn ratio correlated with teacher-rated score for inattention (r = 0.298, p = 0.015). Significant associations of Se and Pb with parent- and teacher-rated symptoms were not observed. The results of this study indicate that there are alterations in plasma levels of Cu and Zn as well as significant relationships to symptoms of ADHD.