Attention-deficit/hyperactivity disorder (ADHD) is a common neurobehavioural disorder that has been related to the brain’s chemistry and anatomy. ADHD is a persistent pattern of inattention and/or hyperactivity/impulsivity that occurs more frequently and more severely than is typically seen in people at comparable levels of development. Symptoms must occur for at least six months and some symptoms have been present since before the age of 7 years.

ADHD begins in childhood and symptoms can persist into adulthood as well. While some children outgrow ADHD, as many as 60% continue to have features of ADHD persisting into adulthood.

According to the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) (a physicians manual for diagnosis), the symptoms of ADHD fall into the following categories: inattention, hyperactivity/impulsivity, and a combination of the two.