Age of Onset
Attention-deficit/hyperactivity disorder is just what it sounds like and usually hits somewhere from ages 3 to 6, though it can strike later.
When It's Nothing
One of the things that makes ADHD difficult to diagnose is that it's hard to find a kid who's not hyperactive or short on attention some of the time. Don't assume every wild mood is ADHD. And since the disorder is more common in boys than in girls, it's easy to mistake gender-typical rambunctiousness for a problem. Undetected hearing or vision problems or common learning disorders may also masquerade as ADHD.
When To Seek Help
Kids who talk nonstop, have difficulty following directions, become bored very easily, can't complete tasks or can't sit still even during a meal may be showing signs of ADHD. Impulsivity is also an important sign though it's a tricky one because most kids lack good impulse control. The key is severity: children who always have trouble waiting their turn or seem incapable of letting an adult finish speaking without interrupting are likelier to have ADHD than kids who sometimes behave that way.
Behavioral therapy to teach children to organize their thoughts, control impulses and reward themselves for achieving goals can help. Stimulant medications, which paradoxically improve focus, are a common part of therapy.