Evaluation of Biomarkers of Oxidative Stress in Attention-Deficit/ Hyperactivity Disorder (ADHD)

Abstract

Biomarkers of oxidative stress and ADHD in children and adolescents are critically reviewed. They are divided in two groups: biomarkers of oxidative stress (general, proteins, including enzymes and non-protein biomarkers) and biomarkers of specific oxidative damage. Observed associations between concentration levels and ADHD symptoms are nearly always contradictory, which is partly due to aetiological a phenotypic complexity of the disorder. Some trends could be observed: lower ferritin and zinc levels, lower total antioxidant status (TAS), higher total oxidant stress (TOS) and higher oxidative stress index (OSI) are associated with ADHD. Even when there is a correlation most authors claim that this relationship is not causative, as illustrated by placebo-controlled trials reporting conflicting evidence on efficacy of supplementation. Well-defined studies could shed more light on their significance in this disorder by observing changes in concentration levels of the various biomarkers and ADHD symptoms before and after treatment with therapeutics.