Late-onset ADHD in adults: Milder, but still dysfunctional

Abstract Objective The requirement in classificatory systems that some impairment from attention-deficit/hyperactivity disorder (ADHD) symptoms starts before 7 years of age (age of onset of impairment criteria – AOC) has been harshly criticized. Although there is evidence that late-onset ADHD is a valid diagnosis, little is known about the role of age of onset of impairment on the clinical profile of adult patients. Methods The diagnoses of 349 adults with ADHD followed DSM-IV criteria. ADHD and oppositional defiant disorder (ODD) were evaluated with the K-SADS-E, and other comorbidities with the SCID-IV and the MINI. Subjects were divided in early and late-onset groups (age of onset of impairment between 7 and 12 years old). The effect of age of onset over clinical and demographic characteristics was tested by regression models. Results Late-onset subjects were diagnosed later ( P = 0.04), had a lower frequency of problems with authority and discipline ( P = 0.004), and lower scores in SNAP-IV ( P < 0.001) and in Barkley’s scale for problems in areas of life activities ( P = 0.03). On the other hand, late-onset patients presented a higher prevalence of comorbid general anxiety disorder (GAD) ( P = 0.01). Both groups had a similar profile in the remaining comorbidities and sociodemographic characteristics. Conclusions This study provides initial evidence that adults with late-onset ADHD have less severity, lower frequency of externalizing symptoms and increased comorbidity with GAD, but similar profile in other comorbidities. In addition, the data suggest that late-onset patients have a higher probability of delayed diagnosis despite the significant impairment of their condition.