Catecholamine functioning in children with traumatic brain injuries and children with attention-deficit/hyperactivity disorder.

Recent studies suggest that children with attention-deficit/hyperactivity disorder (ADHD) and children with traumatic brain injuries (TBI) show changes in similar neuronal networks, including the dopaminergic (DA) and norepinephrinergic (NA) systems. Therefore, indirect measures of catecholamine activity were assessed. Twenty-six children with TBI, 31 children with ADHD, and 26 normal controls, 8 to 12 years of age, were investigated with a 90-min cognitive test battery. Before and after the tests, urine samples were collected to measure catecholamine activity in response to cognitive stress. Spontaneous eyeblinking as an indirect measure of DA activity was counted. Children with TBI and ADHD excreted significantly more normetanephrine in resting situations and less epinephrine (EPI) after cognitive stress, and showed a decreased blink rate compared to normal controls. Children with TBI also showed a higher excretion of metanephrine in the resting situation in comparison to children with ADHD and controls. Whereas children with ADHD showed a higher tonic activity of the NA system and a less adaptive EPI excretion in response to cognitive stress, children with TBI seem to be additionally impaired in their tonic EPI excretion. Our study provides further support for similar but also different neurobiochemical characteristics in both groups.