ADHD News & Research

Adult ADHD: A Different Disorder from Childhood ADHD?

A new study with surprising results seems to indicate that adult ADHD and childhood ADHD may be separate disorders, but more evidence is needed.

Surprising findings from a recent study indicate that, despite what was previously thought, childhood ADHD and adult ADHD may be different conditions, unrelated to one another.

The researchers didn’t hypothesize the results beforehand, and they caution that the results need to be replicated before any conclusions can be made. But the unexpected nature of the results should be noted, they say, and it’s “imperative” that it be fully explored.

The study looked at 1,037 adults born in New Zealand between 1972 and 1973. Based on parent-reported diagnoses, researchers identified 61 individuals – or about 6 percent of the group – that had ADHD at the ages of 11, 13, and 15. When the subjects reached adulthood, researchers conducted extensive diagnostic interviews and determined that 31 had adult ADHD – or about 3 percent.

These are fairly standard diagnosis rates for both groups, but with one twist: They barely overlapped, with only three of the 61 ADHD children retaining the diagnosis until adulthood. The other 28 adults who were diagnosed with ADHD hadn’t shown enough symptoms during childhood to warrant a diagnosis. Males made up the majority of the childhood diagnoses, but, by the time adulthood rolled around, the gender balance of diagnoses had evened out somewhat.

Up to this point, most scientists hypothesized that when ADHD was diagnosed in adulthood, it was simply missed in childhood. Now, however, researchers wonder if there may be an adult-onset form of ADHD, wholly separate from childhood-onset attention deficit.

This isn’t certain, however. While many of the children had outgrown a formal diagnosis, some still struggled with executive functions and handling responsibilities like finances or organization – hallmark symptoms of adult ADHD. But the researchers still conclude that, based on these results, adult-onset ADHD may be a “bona fide” disorder that needs to be further explored.

“Unfortunately, the assumption that adult ADHD is the same as childhood ADHD, that its causes have already been researched, may be discouraging research into adult ADHD,” the researchers write. “If our finding…is confirmed by others, then the etiology for adults with an ADHD syndrome will need to be found.”