Saturday, October 26, 2002
October 25, 2002 05:25 PM ET
By Paula Moyer
SAN FRANCISCO (Reuters Health) - Adults with attention-deficit/hyperactivity disorder (ADHD) show a different pattern of brain activation when performing memory tasks than adults without the condition, a Massachusetts researcher reported here at the American Academy of Child and Adolescent Psychiatry's annual meeting.
Functional magnetic resonance imaging (fMRI) scans showed that a certain region of the brain normally activated during working memory tasks was not active in ADHD adults. This finding lends further validity to the concern that ADHD symptoms can persist into adulthood, said Dr. Larry Seidman, a staff psychologist and researcher at Massachusetts Mental Health Center and Massachusetts General Hospital in Boston.
"We know that there are brain abnormalities, such as reduced brain volume, in children with ADHD," he told Reuters Health. "We need to know if those abnormalities persist into adulthood." He noted that 30% to 60% of children with ADHD still have symptoms as adults.
The study, which is ongoing, focused on working-memory deficits, which are considered hallmarks of ADHD. The investigators sought to determine whether adults with ADHD differ from controls in activating two parts of the brain, the prefrontal cortex and the anterior cingulate, on a working-memory task.
The initial sample consisted of six people with ADHD and five "controls" without the disorder. The ADHD study participants were all right-handed, native English speakers with IQs of at least 80. They had either normal vision or correction to normal, had been diagnosed with ADHD in childhood, and had a family history of ADHD. Seidman said that he and his team of investigators anticipate that the study sample will grow to include 12 people in each group.
The working memory tests consisted of several tasks that required the individuals to temporarily retain a piece of information in a distracting environment. Two tasks involved counting and articulating colors while coping with distracting information, such as the word "red" printed in blue. Other components of the task required study participants to retrieve information from previous tasks.
Even though the study participants with ADHD were able to complete the tasks, their reaction times were somewhat longer than those of controls, Seidman said. The fMRI studies showed that the anterior cingulate of the brain, which is involved in working memory, failed to activate in ADHD patients, in contrast to controls.
"These findings are consistent with previous research showing excess activation in posterior areas of the brain for ADHD adults and not controls," Seidman said. He noted that the effects of drug treatment for ADHD on brain function are not known.