A Study to Evaluate the Efficacy and Safety of Two Doses of PF-03654746 in Adults With Attention Deficit Hyperactivity Disorder (ADHD).

Dosage Form: 0.5 mg capsules of PF-03654746 Dosage: 0.5 mg QD for Days 1-7, then 1.0 mg QD Days 8-14, then 2.0 mg QD Days 15-21

Dosage Form: matching placebo capsules Dosage: Subjects will take two placebo capsules each morning throughout the 3 week double-blind treatment placebo treatment period.

Dosage Form: 0.5 mg capsules of PF-03654746 Dosage: 1 mg (2 x 0.5 mg capsules) of PF-03654746 given daily for three weeks