IRCT2013050413215N1 IRCT 2013-07-31 Vice Chancellor for Research, Shahid Beheshti University of Medical Sciences The Comparison of Aripiprazole versus Risperidone in Attention Deficit Hyperactivity Disorder The Comparison of Aripiprazole versus Risperidone in Attention Disorder Hyperactivity Disorder in Children Under Six Years old age 2012-02-29 anticipated 40 Complete https://irct.ir/trial/13151 interventional Randomization: Randomized, Blinding: Triple blinded, Placebo: Used, Assignment: Parallel, Purpose: Treatment. 2-3 Attention Deficit Hyperactivity Disorder. Intervention 1: intervention group: The starting dosage of Aripiprazole is 1.25 mg daily and it will increase 1.25 mg per day every other week depends on the child response. At the same time, they will receive placebo of Risperidone that is similar to one mg tablet. The starting dosage of that is 1/4 of tablet per day. Placebo will titrate upward with 1/4 tablet each time the clinician increase the dosage of Aripiprazole. Intervention 2: Control group: The starting dosage of Risperidone is 0.25 mg daily and it will increase 0.25 mg per day every other week depends on the child response. At the same time, they will receive placebo of Aripiprazole that is similar to five mg tablet. The starting dosage of that is 1/4 of tablet per day. Placebo will titrate upward with 1/4 tablet each time the clinician increase the dosage of Risperidone.