Adrenomedullary function during cognitive testing in attention-deficit/hyperactivity disorder

Objective: Reported correlations between epinephrine (EPI) excretion and cl assroom performance, the cognition-enhancing effects of EPI infusion, incre ased EPI excretion with stimulants, and reports of decreased EPI excretion in attention-deficit/ hyperactivity disorder (ADHD) suggest that sympathoad renomedullary function might be altered in ADHD. This hypothesis was tested by examining sympathetic and adrenomedullary functioning during cognitive testing in boys with diagnosed ADHD. Method: Urinary excretion of EPI and n orepinephrine during a 3-hour cognitive test battery was assessed in 7- to 13-year-old boys. Excretion rates (nanograms per hour per square meter of b ody surface area) were determined in 200 individuals with ADHD (diagnosed a ccording to DSM-IV criteria), with or without co-occurring oppositional def iant/conduct disorder or learning disorder. A non-ADHD contrast group (n = 51) with similar comorbidity was also studied. Results: Substantially lower (mean +/- SE) urinary EPI excretion was observed in the ADHD-inattentive s ubtype (n = 71) compared with the control group (200 +/- 22 Versus 278 +/- 24 ng/hr/m(2); F = 5.99, p = .015, critical alpha = .017). No diagnostic gr oup differences were seen for norepinephrine excretion. Correlational analy sis of both parent- and teacher-rated behaviors revealed that inattention f actors consistently negatively predicted urinary EPI excretion. Conclusions : The data extend findings of lower adrenomedullary activity during cogniti ve challenge in individuals with ADHD and suggest that the alteration is as sociated with inattentive behavior.