At what age does ADHD most often surface?

The disorder affects individuals of all ages. Of the millions of visits for ADHD to community physicians, about 5% are preschoolers, approximately 66% were elementary school-age, 20% were teenagers, and 15% were adults. ADHD is, however, most often diagnosed in elementary school-age children. Some children are diagnosed later during their junior high school and high school years. It also is not unusual for individuals to receive their first diagnosis of ADHD as adults. Interestingly, many parents first recognize that they have ADHD when it is diagnosed in their child. As this disorder was not diagnosed very frequently years ago, many individuals went through their school years with undiagnosed ADHD. Subsequently, when parents see their children experiencing similar difficulties, they remember their own history, are able to relate, and confirm their own undiagnosed disorder.

ADHD can be diagnosed in preschoolers. Indeed, the peak age of onset, which is different from the age at diagnosis, may be between ages 3 and 4. Not surprisingly, severity affects the age at which ADHD is first noticed, with those more severely affected presenting at a younger age.