This study followed young adults who had been diagnosed with ADHD as children at a Pittsburgh clinic. It compared 200 of them (mean age 20.20 years, most male) with 121 similar adults who did not have ADHD. Fewer than 10% of the ADHD group were taking stimulant medication.
Most of the ADHD group still showed high symptom levels and real problems in daily life. But few met the full DSM symptom count for adults, whether by parent report (12.0%) or self-report (9.6%).
Who gave the report mattered a lot. Parents noticed far more symptoms and impairment than the young adults did. Parents reported meaningful impairment in more than half the group (55.6%), while self-report found it in far fewer (14.6%). Adding self-report on top of parent report did not change the impairment picture in a meaningful way.
The standard DSM items also told the ADHD group apart from controls better than newer adult-specific items, because controls often endorsed the adult items too. When the parent-reported count needed for a diagnosis was lowered to four, the share of the ADHD group who qualified rose from 12.0% to 39.9%, while controls stayed under 3%.
The authors suggest that diagnosing ADHD in young adults with a childhood history should lean on informant reports, keep the DSM items with a lower symptom count, and stress real impairment.
Source: Sibley M, Pelham W, Molina B, et al.. When diagnosing ADHD in young adults emphasize informant reports, DSM items, and impairment.. Journal of Consulting and Clinical Psychology (2012). doi:10.1037/a0029098