Implications of early versus late onset of attention-deficit/hyperactivitydisorder symptoms

Objective: The current diagnostic criteria for attention-deficit/hyperactiv ity disorder (ADHD) require that symptoms emerge prior to age 7 in order fo r a formal diagnosis to be considered. However, this age-of-onset criterion (AOC) has recently been questioned on bath theoretical and empirical groun ds. Method: Data from 4 annual waves of interviews with 9- to 16-year-olds from the Great Smoky Mountains Study were analyzed. Results: Confirming pre vious studies, a majority of youths who had enough symptoms to meet criteri a for ADHD were reported to have first exhibited these symptoms prior to ag e 7. Early onset of ADHD symptoms was associated with worse clinical outcom es in youths with the combined subtype of ADHD but not youths with the inat tentive subtype. Conclusions: Findings support the continued inclusion of t he AOC for the assessment of the combined but not necessarily the inattenti ve subtype of ADHD. Too few youths had a late onset of solely hyperactive-i mpulsive symptoms to evaluate the AOC for that group. However, regardless o f the age of onset, youths who had elevated levels of ADHD symptoms were at increased risk for negative outcomes that may necessitate intervention.