Synthesizing a wealth of recent neuropsychological research, this groundbreaking book focuses on the multiple pathways by which attention-deficit/hyperactivity disorder (ADHD) develops. Joel T. Nigg marshals the best available knowledge on what is actually going on in the symptomatic child's brain and why, tracing the intersecting causal influences of genetic, neural, and environmental factors. In the process, the book confronts such enduring controversies as the validity of ADHD as a clinical construct. Specific suggestions are provided for studies that might further refine the conceptualization of the disorder, with significant potential benefits for treatment and prevention.