Study Says Children Don’t Outgrow ADHD Despite Previous Research
It is widely believed that children or adolescents diagnosed with attention-deficit hyperactivity disorder (ADHD) grow out of the disorder as they get older, but new research suggests that is not the case.
A study from the University of Cambridge published this week in the journal European Adolescent Psychiatry, indicates that young adults who were diagnosed with ADHD when they were younger showed notable differences in brain structure, as well as poorer memory performance compared to peers with no history of ADHD.
The findings lead the researchers to believe aspects of the disorder may carry over into adulthood, even in those who were not diagnosed as adults.
Current data indicates around 9 percent of children ages 4 to 17 have an ADHD diagnosis, with between 10 to 50 percent of these children continuing to have the disorder as adults. This has caused some psychologists to believe that some children may outgrow the condition as the brain develops into adulthood. However, the researchers of the newest study say past research has failed to take into account brain changes characteristic of ADHD.
For the study, researchers followed up with 49 young Finnish individuals in their early 20s who had previously been diagnosed with ADHD at the age of 16. These individuals underwent fMRI scans to evaluate their brain structure as well as taking tests of memory function.
According to the findings, nearly all the individuals showed reduced brain volume and significantly poorer memory function when compared to a group of control subjects with no history of the disorder.
Brain volume reductions were most commonly observed in the caudate nucleus, a region of the brain linked with the ability to integrate information from different parts of the brain and storing and processing memories.
To further investigate how these findings manifest themselves, the researchers also asked the participants to complete a working memory test while their brain was being scanned using fMRI. Nearly a third of the subjects with a history of ADHD failed the memory test while only 5 percent of the control group failed.
The researchers also observed those with ADHD showed less activity in the caudate nucleus when taking the memory test, indicating poor memory may be related to a sluggish response in this part of the brain.
“In the controls, when the test got harder, the caudate nucleus went up a gear in its activity, and this is likely to have helped solve the memory problems,” Dr. Graham Murray, a professor of psychiatry at Cambridge and the study’s lead author, said in a written statement. “But in the group with adolescent ADHD, this region of the brain is smaller and doesn’t seem to be able to respond to increasing memory demands.”
“We are still learning about ADHD in adults, and it is still an under-researched area, but I think there is indeed a growing recognition there are indeed many adults of a whole range of ages who have ADHD and who have never been diagnosed,” he said. “Many of these people are now coming forward for treatment.”