Selegiline in ADHD adults: Plasma monoamines and monoamine metabolites

Plasma monoamines and monoamine metabolites were assessed before and during selegiline treatment in adults with attention deficit/hyperactivity disorder (ADHD). Selegiline, at low dose, is a selective monoamine oxidase inhibitor type B (MAOI-B). After 2-week placebo baseline, 36 ADHD adults were randomized to 6-week placebo or 20 mg/day or 60 mg/day selegiline, followed by 2-week posttreatment placebo. Twenty-seven subjects continued into a 6-week 20-mg/day or 60-mg/day selegiline period. Behavioral variables included self-rated scores on the Conners' Abbreviated Teacher Rating Scale (Conners-ATRS) and performance on a Continuous Performance Task (CPT). Plasma samples were assayed for amines (dopamine, norepinephrine, epinephrine), precursor (DOPA), and metabolites (HVA, DOPAC, DHPG, normetanephrine, metanephrine, 5-HIAA). Selegiline produced dose-dependent changes in monoamine metabolites and DOPA plasma levels. Dopaminergic indices were associated with ADHD symptom severity (Conners-ATRS) and noradrenergic indices with CPT performance. Serotonergic metabolism, challenged by selegiline, correlated with clinical changes. These findings support a multisystem dysfunction underlying ADHD pathophysiology.