Attention deficit hyperactivity disorder (ADHD) is one of the most prevalent psychiatric disorders of childhood. Although once a vigorously debated issue, it is now accepted that ADHD can be reliably distinguished from other behavioural problems in childhood and adolescence (Goldstein, 1999). The disorder is also recognized as existing beyond childhood (Tannock, 1998), resulting in the need for clinicians to increase their understanding of the various developmental outcomes and age-related changes in presentation and response to treatment.

This chapter begins by summarizing the research and clinic-based evidence regarding the nature of ADHD. The manner in which the disorder can affect individuals as they mature from childhood to adulthood is then discussed and various intervention strategies are presented.

Diagnostic classifications and prevalence

An important difference exists between simple hyperactivity, which describes a tendency to behave in an inattentive, overactive and impulsive way, and the psychiatric diagnostic category of ADHD. Most children are hyperactive in some situations. Indeed, hyperactivity is a trait, not unlike intelligence, that appears to be normally distributed in the general population (Taylor et al., 1991). However, in most children, their behaviour is regulated by environmental demands. This influence, and accompanying behavioural control, increases with age and maturity. Society expects increased behavioural control as children develop. At school, for example, a 5-year-old child might be expected to sit quietly listening to a 10-minute story, whereas a 15-year-old child would be required to sit and attend for a 45-minute lesson.