1. Subject has a current comorbid psychiatric disorder that is either controlled with medications prohibited in this study or is uncontrolled and associated with significant symptoms. Prohibited disorders include those associated with diagnoses including but not limited to any severe comorbid Axis II disorder or severe Axis I disorder (such as Post Traumatic Stress Disorder [PTSD], psychosis, bipolar illness, pervasive developmental disorder, severe obsessive compulsive disorder, severe depressive or severe anxiety disorder). Other symptomatic manifestations (such as agitated states) that contraindicate treatment with SPD489 or confound efficacy or safety assessments in the opinion of the examining physician are also prohibited. Comorbid psychiatric diagnoses will be established by the psychiatric evaluation that includes the Structured Clinical Interview for DSM-IV-TR disorders (SCID-I).