Attention-Deficit Hyperactivity Disorder (ADHD) is generally considered to be a developmental disorder, largely neurological in nature, affecting about 5% of the world's population. The disorder typically presents itself during childhood, and is characterized by a persistent pattern of inattention and/or hyperactivity, as well as forgetfulness, poor impulse control or impulsivity, and distractibility. ADHD is currently considered to be a persistent and chronic condition for which no medical cure is available. ADHD is most commonly diagnosed in children and, over the past decade, has been increasingly diagnosed in adults. About 60% of children diagnosed with ADHD retain the disorder as adults. The disorder appears to be highly heritable, with contributions on occasion from trauma or toxic exposure. Methods of treatment usually involve some combination of medications, behaviour modifications, life style changes, and counseling. ADHD is a developmental disorder that is often said to be neurological in nature. The term "developmental" means that certain traits such as impulse control significantly lag in development when compared to the general population. This developmental lag has been estimated to range between 30-40 percent in ADHD sufferers in comparison to their peers; consequently these delayed attributes are considered an impairment. ADHD has also been classified as a behavior disorder and a neurological disorder or combinations of these classifications such as neurobehavioural or neurodevelopmental disorders.