Adult attention-deficit/hyperactivity disorder (ADHD) was a rare diagnosis 30 years ago, but epidemiological studies in the 2000s estimated a prevalence between 2% and 5%.1 More recent reports suggest there may be a rapid increase in new diagnoses, much as has been found for childhood ADHD.2 Changes to diagnostic criteria in DSM-5 (compared with DSM-IV) are likely to lead to further increases. These include lowering the number of symptoms for diagnosis in adults from 6 to 5 and raising the age at onset of childhood symptoms from 7 years to 12 years. Additionally, there has been a switch from an emphasis on clinically significant impairment in DSM-IV to the more lenient requirement that symptoms “interfere” or “lower quality” of day-to-day functioning.