Attention Deficit Disorder (ADD) is a neurological disorder that affects children from the first months of their lives, through their school years, and into adolescence and adulthood. It may be accompanied with hyperactivity and is then known as Attention Deficit Hyperactivity Disorder (ADHD). The hallmarks of ADD are difficulties with attention, impulsivity and hyperactivity, which can be in varying proportions. Individuals with the disorder have difficulty paying attention, tend to act quickly without thinking things through, rarely learn from past mistakes and have trouble sitting still for lengthy periods.

Until recently, Attention Deficit Disorder was considered to be a disorder of childhood only. It is now recognised that up to 70 % of all children with ADD continue to exhibit symptoms of the disorder as adults. The condition does not always resolve in childhood as previously thought. When ADD persists into adulthood it is often associated with secondary problems such as anxiety, depression, and drug and alcohol abuse. Management of the problem in childhood decreases the risk of these secondary problems occurring later in life.

The onset of symptoms must occur before the age of seven and persist for six months or longer. In other words, a child cannot suddenly develop ADD; rather the signs must have been present for a relatively long time. No two individuals with ADD present exactly the same profile i.e. a child may have poor concentration and be impulsive without being hyperactive. Since there is no "gold standard" for testing ADD (the diagnosis made is a differential diagnosis and one of exclusion) it is necessary to pay careful attention to the developmental history of the child and his family's history in the initial assessment. Recent technological advancements such as continuous performance tests (CTP’s) and the quantitative electroencephalograph (qEEG) are now being used to aid in the diagnosis.