Attention deficit hyperactivity disorder (ADHD) is a psychiatric condition affecting young children and adolescents, characterised by inappropriate high levels of hyperactivity, inattention and impulsivity. A strong genetic basis for ADHD has been documented by family, twin and adoption studies. Dopamine, a neurotransmitter, has been implicated to play an important role in ADHD since the most frequently prescribed drugs for ADHD are targeted at the dopaminergic system. Unfortunately, the disease continues into adulthood in 30-70% of patients. It has been proposed that ADHD may lead to memory deficits, delinquency, substance abuse, and problematic personality disorders, in addition to being one of the highest risk factors for other mental illnesses. This book gathers the latest research from around the globe in this field.