Urinary catecholamines in attention-deficit hyperactivity disorder with and without comorbid anxiety

Area of Science:

• Neuroscience
• Child Psychiatry
• Pharmacology

Background:

• Attention-deficit hyperactivity disorder (ADHD) is a common neurodevelopmental disorder.
• Noradrenergic and adrenergic systems play crucial roles in attention, arousal, and stress response.
• Comorbid anxiety disorders are frequent in children with ADHD.

Purpose of the Study:

• To investigate differences in noradrenergic and adrenergic functioning between children with ADHD and those with comorbid anxiety.
• To compare ADHD children (with and without anxiety) to healthy controls.

Main Methods:

• Urinary excretion of norepinephrine (NE), epinephrine (EPI), and their metabolites (normetanephrine, metanephrine) was measured over 2 hours.
• Subjects underwent a standardized series of mentally stressful tasks during sample collection.
• Comparison groups included ADHD children with comorbid anxiety (ADHD/ANX), ADHD children without anxiety, and normal controls.

Main Results:

• Children with ADHD, irrespective of anxiety, exhibited higher urinary excretion of normetanephrine and vanillylmandelic acid compared to controls.
• ADHD-only group showed lower norepinephrine/normetanephrine and epinephrine/metanephrine ratios than controls.
• Children with ADHD/ANX excreted significantly more epinephrine than children with ADHD alone.

Conclusions:

• Children with ADHD may possess elevated tonic noradrenergic system activity compared to neurotypical individuals.
• Increased adrenergic activity in children with comorbid ADHD/ANX can distinguish them from those with ADHD without anxiety.