Attention Deficit Tied to Brain’s Development
Children with attention deficit and hyperactivity disorder (ADHD) are missing critical neural wiring in the brain that is needed for attention, according to a recently released study by a UC Irvine neurologist.
UCI College of Medicine pediatric neurologist Dr. Pauline Filipek and a team of researchers discovered that children with ADHD have smaller neural connections in parts of the brain that help humans process attention.
By using special computer software that analyzes MRI scans of brains, the researchers found that a problem with the physical development of the brain’s neural networks during childhood may be a factor in ADHD, a disorder that affects about 5% of children in the United States.
Previous research had identified three regions of the brain as affecting attention. Adults with lesions in these parts of the brain from such problems as strokes often lost attention skills.
“We applied those three networks to children for the first time,” Filipek said Monday, “and found that’s where the differences were most pronounced.”
Researchers examined 30 teenage boys--15 who were developmentally normal and 15 who had received a clinical diagnosis of ADHD, a condition characterized by short attention span, impulsiveness and sometimes restlessness. Previous research has found that ADHD stems from a genetic malfunction in the neurotransmitters, or chemicals that fuel the attention and impulse centers of the brain.
The computer analyses of the MRI scans showed that the brains of children with ADHD had smaller neural wirings in three key regions of the brain--the same ones involved in adults who had lost attention skills. Of these sections, two frontal areas help humans be alert and focus, and a back part allows them to orient themselves.
The study found that current medications being used to treat ADHD, such as the stimulant Ritalin, are not effective in ADHD children whose posterior region is smaller.
A nationally known psychologist who is studying the effects of Ritalin on children with ADHD said the conclusions fit with what he has seen.
“That makes sense,” said George DuPaul, an associate professor at Lehigh University’s School of Psychology in Pennsylvania. “The posterior part of the brain is controlling different things and Ritalin may not have any effect in that part of the brain.
“Each new study is another brick in the wall,” DuPaul added. “Perhaps this will provide a biological marker to help us determine who responds to medication.”
Meanwhile, the cause of the underdeveloped brain regions remains unknown. Filipek said she will expand the research to test more children, both boys and girls, to explain exactly how the smaller neural connections specifically result in ADHD.
“What this means for parents is that we’re on the path to possibly finding specific, organic reasons for ADHD, which may open the door to new therapies and treatments,” Filipek added.
Dr. Bunni Tobias, a Lake Forest clinical specialist who works with hundreds of children with ADHD, finds the work promising. She argues that too often, children receive a misdiagnosis of ADHD because some of its common signs--including short attention span, impulsiveness and restlessness--are similar to those of other conditions.
“Filipek is proving that the solutions to ADHD are bigger and more complex than prescribing Ritalin,” said Tobias, who favors finding other treatments for the condition. “There are many things that mimic the symptoms of ADHD, and this helps others ask more questions and better understand ADHD.”
Filipek’s study began in 1990, when she was at Harvard Medical School working with five other researchers. She completed this study after she came to UCI in 1994. Her work was published recently in the medical journal Neurology.
