The thinking among scientists regarding attention deficit hyperactivity disorder, or ADHD, has long been this: It’s something you develop in childhood, as a highly distractible little kid. Decades ago, the consensus among the scientific community was that this was a childhood-only disorder, disappearing by early adulthood, as Quartz’s Jenny Anderson reports. This, of course, turns out to be not so true, but still the evidence has suggested that if an adult has ADHD, surely he or she showed signs of of the attention disorder as a kid, too.
All of which is what makes two longitudinal studies out this week in JAMA Psychiatry so very interesting. Each of them suggests that it’s possible for ADHD to show up for the first time in adulthood — even if those adults never had attention problems or symptoms of ADHD in childhood.
A study led by researchers at King’s College in London, for example, tested the same 2,200 twins for ADHD starting at age 5, then following up with them at ages 7, 10, 12, and 18. At that most recent check-in — when these children had grown into young adults, in other words — 70 percent of those 18-year-olds who showed signs of ADHD had not shown those symptoms at any of the earlier check-ins. Another longitudinal study led by scientists in Brazil showed similar results.
Also of note: Though ADHD is typically, if incorrectly, conceived of as a problem mostly affecting hyperactive young boys, these findings show an almost even split between genders. Actually, women were slightly more likely to develop ADHD in adulthood, though this could easily be because symptoms of the disorder are often overlooked in girls.
Though ADHD isn’t exactly common among adults, it’s not uncommon either, affecting about four percent of the population, Jessica Agnew-Blais, co-author of the U.K. study, told Anderson. These new findings suggest, Agnew-Blais added, that the “absence of a childhood diagnosis should not prevent adults with ADHD from receiving clinical attention.” As is usually the case with shiny new scientific findings, more research is needed. For now, though, the evidence is hinting that it may be time to reframe the conversation around attention disorders.