Studies show that young children diagnosed with the condition between the ages of two and four have a 50 percent chance of outgrowing it, while children diagnosed after age five have only a 25 percent chance. Considering the odds, some experts believe that when it comes to diagnosing ADHD, the younger the better.

On the other hand, diagnosing an infant or preschooler with a disorder that isn't normally diagnosed until age six opens a Pandora's box. You and your child could go through a lot of expense and heartache for nothing. There's also the chance that diagnosing an infant or toddler with what appears to be ADHD will distract you or your physician from recognizing telltale signs of disorders that mimic ADHD, or have similar symptoms, and which are far more common in infants and toddlers.