Authors: Louise White
New research from the University of Cambridge, UK and the University of Oulu, Finland suggests that features of attention deficit/hyperactivity disorder (ADHD) may continue into adulthood, despite sufferers no longer meeting the diagnostic criteria for the disorder. The findings were published recently in the journal European Child Adolescent Psychiatry.
ADHD is usually diagnosed during childhood or early adolescence, and is characterized by inattentiveness, hyperactivity and impulsiveness. Although much is understood about the disorder in childhood, little rigorous evidence exists concerning the persistence of the disorder into adulthood, despite some estimates indicating that 10–50% of children with ADHD may carry it into adulthood To date, most of the research in this area has focused on interview-based assessments, rather than investigating brain structure and function, although some have hypothesized that as the brain develops following adolescence children ‘grow out’ of ADHD.
Lead author, Graham Murray (University of Cambridge) and his team examined the brain structure and memory function of 49, 20–24 year olds, that had been diagnosed with ADHD at the age of 16. They then compared their findings with a control group of 34 young adults.
The results suggested that the group that had previously been diagnosed with ADHD had reduced gray matter in the caudate nucleus, an important brain region for the support of vital cognitive functions such as memory. This was regardless of whether or not the subjects had continued to meet the standard diagnostic criteria for ADHD. The team highlighted the importance of the gray matter deficits in further functional MRI experiments measuring the brain activity of all subjects during a working memory test.
Murray stated: “We know that good memory function supports a variety of other mental processes, and memory problems can certainly hold people back in terms of success in education and the workplace. The next step in our research will be to examine whether these differences in brain structure and memory function are linked to difficulties in everyday life, and, crucially, see if they respond to treatment.”
This research indicates that brain structure and function may continue to be abnormal for a person previously diagnosed with ADHD, irrespective of whether or not the subject continues to meet the checklist criteria for diagnosis.