NIMH collaborative multisite multimodal treatment study of children with ADHD: I. Background and rationale.

OBJECTIVE The National Institute of Mental Health's recently initiated 5-year, multisite, multimodal treatment study of children with attention-deficit hyperactivity disorder (MTA) is the first major clinical trial in its history focused on a childhood mental disorder. This article reviews the major scientific and clinical bases for initiating the MTA. METHOD A selective review of the literature is presented in the service of describing the estimated prevalence of ADHD among children and adolescents, its core clinical features, evidence concerning psychopharmacological and psychosocial treatment effects, and related research issues and trends leading to the development of the MTA. RESULTS Despite decades of treatment research and clinical practice, there is an insufficient basis for answering the following manifold question: under what circumstances and with what child characteristics (comorbid conditions, gender, family history, home environment, age, nutritional/metabolic status, etc.) do which treatments or combinations of treatment (stimulants, behavior therapy, parent training, school-based intervention) have what impacts (improvement, stasis, deterioration) on what domains of child functioning (cognitive, academic, behavioral, neurophysiological, neuropsychological, peer relations, family relations), for how long (short versus long term), to what extent (effect sizes, normal versus pathological range), and why (processes underlying change)? CONCLUSIONS The important scientific, clinical, and public health issues nested within this manifold question provide both the impetus and scaffolding for the MTA.