A spectrum of neurological disorders, increasingly recognised as affecting children, young people and adults, and manifesting themselves (very simplistically) as

• overactive behaviour/hyperactivity
• impulsive behaviour
• difficulty in paying attention

These may cause difficulties within families and in school. ADD refers to problems in concentration and attention; ADHD refers to ADD plus overactive and impulsive behaviours. The "official" UK term, Hyperkinetic Disorders, covers the aspects of hyperactivity and impulsive behaviours. The causes of ADD/ADHD appear (currently) to be a mixture of genetic and environmental factors (possibly including diet). Children who have suffered brain injury or illness may also exhibit similar symptomatic behaviours.