Sixty percent of children with ADHD in a recent study demonstrated persistence of symptoms into their mid-20's, and 41 percent had both symptoms and impairment as young adults.
Investigators noted that rates of ADHD persistence into adulthood have varied greatly in earlier studies, depending on how information is collected and analyzed. In a 16-year follow-up of the Multimodal Treatment Study of Children with ADHD (the "MTA"), they found that a combination of parent and self-reports plus a symptom threshold that is adjusted for adulthood (rather than based on traditional childhood definitions of ADHD) may be optimal.
"There has been a lot of recent controversy over whether children with ADHD continue to experience symptoms into adulthood," said Dr. Margaret Sibley, lead author of the Journal of Child Psychology and Psychiatry study. "This study found that the way you diagnose ADHD can lead to different conclusions about whether or not an adult still has the disorder that started in childhood. First, if you ask the adult about their continued symptoms, they will often be unaware of them; however, family members or others who know them well often confirm that they still observe significant symptoms in the adult." Dr. Sibley added that if the classic childhood definition of ADHD is used when diagnosing adults, many cases will be missed because symptom presentation changes in adulthood. "By asking a family member about the adult's symptoms and using adult-based definitions of the disorder, you typically find that around half of children with moderate to severe ADHD still show significant signs of the disorder in adulthood."
Article: Defining ADHD symptom persistence in adulthood: optimizing sensitivity and specificity, Margaret H. Sibley, James M. Swanson, L. Eugene Arnold, Lily T. Hechtman, Elizabeth B. Owens, Annamarie Stehli, Howard Abikoff, Stephen P. Hinshaw, Brooke S. G. Molina, John T. Mitchell, Peter S. Jensen, Andrea L. Howard, Kimberley D. Lakes, William E. Pelham, and for the MTA Cooperative Group, Journal of Child Psychology and Psychiatry, doi: 10.1111/jcpp.12620, published 19 September 2016.