London: Adolescents diagnosed with attention deficit/hyperactivity disorder (ADHD) may perform poorly in memory tests compared to their peers even in adulthood, suggests new research.
ADHD is a disorder characterised by short attention span, restlessness and impulsivity, and is usually diagnosed in childhood or adolescence.
"Memory problems can certainly hold people back in terms of success in education and the workplace,” said lead researcher Graham Murray from the University of Cambridge.
Estimates suggest that more than three in every 100 boys and just under one in every 100 girls has ADHD. Less is known about the extent to which the disorder persists into adulthood, with estimates suggesting that between 10-50 percent of children still have ADHD in adulthood.
The researchers followed 49 adolescents diagnosed with ADHD at age 16, to examine their brain structure and memory function in young adulthood, aged between 20-24 years, compared to a control group of 34 young adults.
The results showed that the group diagnosed in adolescence still had problems in terms of reduced brain volume and poorer memory function, irrespective of whether or not they still met diagnostic checklist criteria for ADHD.
Brain scan showed that the adolescents with ADHD had reduced grey matter in a region deep within the brain known as the caudate nucleus, a key brain region that integrates information across different parts of the brain, and supports important cognitive functions, including memory.
In a memory test, one third of the adolescents with ADHD failed compared to less than one in twenty of the control group (an accuracy of less than 75 percent was classed as fail).
Even among the adolescent ADHD sample who passed the memory test, the scores were on average six percentage points less than controls.
There were no differences in brain structure or memory test scores between those young adults previously diagnosed with ADHD who still met the diagnostic criteria and those who no longer met them.
The study was published in the journal European Child Adolescent Psychiatry.