Basic Facts about ADHD ADHD is an acronym that stands for Attention Deficit Hyperactivity Disorder. This condition was formerly known as Attention Deficit Disorder, though the name was modified when it was noted that the affected people were also prone to severe hyperactivity. ADHD commonly manifests in young children, though most of them carry the traits over into adulthood as well. ADHD is also referred to by some people as the ""single-synapse"" or the ""short attention span"" problem. The reason for this is that ADHD's main characteristics are a marked inability to concentrate on any one thing for very long, accompanied by extremely impulsive behavior where the person doesn't stop to think at all when they get an idea or react to a situation.