Primary Aim: Assess the efficacy and adverse effects of amiloride in medication naive ADHD adults in a placebo controlled study. Hypothesis 1: Amiloride will reduce scores on our primary outcome measure, the Adult Attention-Deficit/Hyperactivity Disorder Investigator Symptom Rating Scale (AISRS) and on our secondary outcome, the ADHD specific Clinical Global Impressions (CGI) improvement scale. Hypothesis 2: Amiloride will be well tolerated and will have few side effects in adults with ADHD.