Stimulant drug response in the predominantly inattentive and combined subtypes of attention-deficit/hyperactivity disorder.

Objective: This study compared the methylphenidate (MPH) dose-response profiles of children with the Predominantly Inattentive (PI) and Combined (CB) subtypes of attention-deficit/hyperactivity disorder (ADHD). It is the first such study to enroll a sample comprised exclusively of children, all but one of whom had no prior exposure to ADHD medications.

Method: The design was a double-blind crossover with 1-week exposures to placebo and low, medium, and high, fixed, three times daily (t.

Neurocognitive functioning in AD/HD, predominantly inattentive and combined subtypes.

The Predominantly Inattentive (PI) and Combined (CB) subtypes of AD/HD differ in cognitive tempo, age of onset, gender ratio, and comorbidity, yet a differentiating endophenotype has not been identified. The aim of this study was to test rigorously diagnosed PI, CB, and typical children on measures selected for their potential to reveal hypothesized differences between the subtypes in specific neurocognitive systems (anterior vs. posterior attentional systems) and processes (arousal vs.