Objectives: Longitudinal studies of children with Attention-Deficit/Hyperactivity Disorder (ADHD) into adolescence have all reported high rates of ADHD. However, findings from studies into adulthood are inconsistent. This article reviews factors that may account for disparate rates found in adult follow-ups, and recommends optimal methodologies for prospective studies of children with ADHD in particular and childhood mental disorders in general.
Method: Follow-up studies of children with ADHD into adulthood are critically reviewed to identify factors that influence adult ADHD prevalence estimates.
Results: Four factors are identified: (1) ascertainment procedure, (2) attrition rate, (3) reporting source, and (4) disorder criteria.
Conclusions: Estimates of the proportion of children with ADHD who will experience symptoms of the childhood syndrome in adulthood are likely to vary considerably, as a function of multiple factors. Several recommendations are made for designing future follow-up investigations.