Method of adult diagnosis influences estimated persistence of childhood ADHD: a systematic review of longitudinal studies

Several studies have questioned the stability of attention-deficit hyperactivity disorder (ADHD) from childhood to adulthood. This systematic review illustrates how variability in diagnostic methods influences adult ADHD persistence estimates. Systematic database searches identified studies reporting adult ADHD persistence rates that were published in English between Jan 1, 1992, and May 31, 2016. Study inclusion criteria were systematic childhood diagnosis of attention-deficit disorder, ADHD, or a research diagnostic protocol that matched DSM-III, DSM-III-R, or DSM-IV standards; mean childhood age of younger than 12·0 years with no participants older than 18·0 years; and mean adult age of 18·0 years or older with no participants younger than 17·0 years. Across 12 included samples, we identified 41 estimates of ADHD persistence, which ranged from 4·0% to 77·0%. Methods of diagnosing ADHD in adulthood varied widely with respect to source of information, diagnostic instruments (eg, rating scales, interviews), diagnostic symptom threshold, and whether impairment was required for diagnosis. Sole reliance on self reports and a strict threshold of six DSM symptoms led to very low persistence estimates. To minimise false-negative and false-positive classifications, recommended methods for determining adult persistence of ADHD include collecting self and informant ratings, requiring the presence of impairment, and using an age-appropriate symptom threshold. Very few persistence estimates utilised these methods, but those that did indicated persistence rates of 40–50%.