What is ADHD?

• ADHD is one of the most common neurodevelopmental disorders in children, affecting a child’s nervous system and brain as they grow.^8-10 While “adult” ADHD is diagnosed in individuals over age 17 years, the symptoms are sometimes partly expressed in childhood, but not diagnosed, and continue into adulthood.¹¹
• ADHD is a chronic, but waxing and waning, disorder with periods of full remission that are more often temporary than sustained.¹² Roughly two-thirds of children with ADHD continue to have impairing symptoms of ADHD into adulthood.¹²
• ADHD as a disorder continues in ~15% of people by age 25 years; symptoms that affect activities of daily living persist in ~65%.^{10, 13} The Who Else Has ADHD? section in this guide talks about who has ADHD in more detail.
• ADHD symptoms in adults may differ from those in children. Inattention symptoms are more likely to continue and decline more slowly with age, while symptoms of hyperactivity and impulsivity may decrease with age.