Richard Barkley study found between 14 - 50% resolution by ages 21 to 27.
Again cannot find a Richard Barkley, but found a Russell Barkley and he basically says that diagnostic criteria are not very good for diagnosing adult ADHD and that accounts for some adults who were diagnosed with ADHD as children as not showing up as ADHD as adults. He hasn’t said it’s because they’re cured….or grew out of it….or it’s resolved.
”Abstract
Objective: While it is increasingly recognized that attention deficit hyperactivity disorder (ADHD) persists into adulthood, there is no consensus on diagnostic criteria for adult ADHD. In this article the authors describe and contrast competing approaches for diagnosis of adult ADHD used in clinical and research practice.
Method: The authors review the Wender Utah criteria, DSM criteria, and laboratory assessment strategies for adult ADHD. Advantages and disadvantages of each approach are described, and recommendations are made as a basis for clinical assessment and future research.
Results: Both the Wender Utah criteria and DSM-based approaches identify significantly impaired ADHD adults with neurocognitive, biological, and treatment response patterns similar to pediatric ADHD patients. The Wender Utah criteria established the need for retrospective childhood diagnosis and recognize developmental differences in adult symptom expression. The Wender Utah criteria fail to identify patients with predominantly inattentive symptoms, exclude some patients with significant comorbid psychopathology, and diverge significantly from the DSM conception of ADHD. The DSM criteria have never been validated in adults, do not include developmentally appropriate symptoms and thresholds for adults, and fail to identify some significantly impaired adults who are likely to benefit from treatment. There are insufficient scientific data to justify use of laboratory assessment measures, including neuropsychological tests and brain imaging, in diagnosing adult ADHD.
Conclusions: Adult ADHD remains a clinical diagnosis. Clinicians should be flexible in application of the current ADHD criteria to adults. Additional research is required to validate adult diagnostic criteria.
pubmed.ncbi.nlm.nih.gov/15514392/
And more recently
Abstract
Objective: To describe adult outcome of people with attention-deficit/hyperactivity disorder (ADHD) diagnosed in childhood and its several key predictors via a review of 7 North American controlled prospective follow-up studies: Montreal, New York, Milwaukee, Pittsburgh, Massachusetts General Hospital (MGH), Berkeley, and 7-site Multimodal Treatment Study of Children With ADHD (MTA).
Method: All studies were prospective and followed children with a diagnosis of ADHD and an age- and gender-matched control group at regular intervals from childhood (6-12 years of age) through adolescence into adulthood (20-40 years of age), evaluating symptom and syndrome persistence, functional outcomes, and predictors of these outcomes.
Results: The rates of ADHD syndrome persistence ranged from 5.7% to 77%, likely owing to varying diagnostic criteria and the source of information (self-report vs informant report) across the studies. However, all studies observed high rates of symptomatic persistence ranging from 60% to 86%. The 7 studies were largely consistent in finding that relative to control groups, research participants with childhood-diagnosed ADHD had significant impairments in the areas of educational functioning, occupational functioning, mental health, and physical health as well as higher rates of substance misuse, antisocial behavior, and unsafe driving. The most consistently observed predictors of functional outcomes included ADHD persistence and comorbidity, especially with disruptive behavior disorders.
Conclusion: Childhood ADHD has high rates of symptomatic persistence, which is associated with negative functional outcomes. Characteristics that predict these negative outcomes, such as comorbid disruptive behavior disorders, may be important targets for intervention.”
pubmed.ncbi.nlm.nih.gov/34116167/