Exploratory Aim 2: Assess effects of amiloride on ADHD-associated clinical features. We will also assess, in an exploratory manner, the effect of amiloride on two clinical features that are not well treated by current ADHD medications: deficits in emotional self-regulation (DESR) and executive function deficit (EFD). Hypothesis 3 predicts that amiloride treatment will reduce symptoms of DESR and of EFD.