December 09, 2007

ADHD Brains Might Need More Growing Time

The causes of attention deficit hyperactivity disorder, commonly known as ADHD, have left the Scientists divided. ADHD affects approximately 3 to 5 percent of school-age children. The different opinions in the scientific community say that it is a developmental delay, while others in the scientific community will argue that the brains of ADHD children are abnormal from birth. But, one big puzzle remains common: Some, but not all, ADHD children seem to "grow out" of the disorder, which can cause restlessness, inattention, and difficulty focusing. This fascinating new finding by researchers at the National Institute of Mental Health, reported in the November 12, 2007 issue of Proceedings of the National Academy of Sciences, has now suggested that almost half of the children with ADHD, the troubling symptoms they experience in childhood could be a result simply of slower—but otherwise normal—maturation of the brain.
Judith Rapoport; one of the coauthors of the study and chief of the child psychology branch at the National Institute of Mental Health; has pioneered efforts to study the relationship between brain structure and mental disorders. In an interview with Mrs. Judith Rapoport, U.S. News asked her what should anxious parents make of these findings. Rapoport cautions that this research is in the early stages. “The delays, which put areas of the brain used in higher order decision making behind schedule by an average of three years, were most evident in areas at the front of the brain's outer covering, or cortex, that house the ability to control thinking, attention, and planning. In some of the children and teens with ADHD, the brain regions reached peak thickness when the children averaged 10.5 years old, compared with 7.5 in children without ADHD,” says Rapoport.
U.S. News asked “You’ve been studying children's brains for almost 20 years to figure out how they develop, and have done MRI brain scans of healthy children, hyperactive children, and some children with mental illnesses like schizophrenia. You say you're very excited about this latest finding. How come?”
Mrs. Rapoport reported, “In our earlier studies, we just looked at brain development, measuring the change in volume in gray matter in children with ADHD and in typically developing children. The results were similar, but they focused only on the size of brain's lobes, which are relatively large. In this latest study, we were able to use new technology and measure the thickness of 40,000 different points in the cortex, each at a different point in the brain. We were then able to follow how that thickness changed over time in 446 children and adolescents [223 with ADHD and 223 controls]. The brain matures from back to front, with very basic things like vision developing first, at the back. When you plot how those brain areas change over time, you end up with a movie that looks like a wave, moving from back to front. We looked at these movies and said, "Oh, my God!" This is what we'd missed in [studying the] lobes, this ripple with a three-year lag. The hyperactivity group was delayed anywhere between two and three years.”
U.S. News asked, “The lateral prefrontal cortex is in the front of the brain, and that's what you saw developing most slowly in the ADHD kids. What does that area of the brain do?” “These are some of the last brain functions to mature. There are some intellectual functions, such as the ability to suppress inappropriate actions and thoughts, focus attention, remember things from moment to moment, and control movement. It may have to do with overall organization. Deficits in all these functions have been associated with ADHD,” said Rapoport.
When asked what does this mean for children who are diagnosed with ADHD?
Mrs. Rapoport said that for some kids, it looks like they're "growing out of it," which is what the grandmothers of kids with ADHD have been saying all along. She said there is very soft data does suggest that the kids who have “later brain maturation” are these "good outcome" kids. The other half are dissimilar.
She went on to say, “It makes sense for two separate reasons. Some of the kids in truth do grow out of ADHD. That's part of why ADHD is such a controversial diagnosis. Every clinician knows somebody who in third grade was always in the principal's office and always in trouble. That kid ends up going to Harvard. All of our biological studies suggest there are subgroups of kids with ADHD who have different-than-normal processes going on in their brains. This may be the most benign one. With other subgroups, the kids may get better because certain parts of the brain get larger to create an alternative intelligence system. They're not the ones who grow out of it. The next step is to connect this to outcomes. That will take us at least two years.”
When she was asked what she would say if I were the parent of a kid with ADHD, what would you tell me to do about this new information?
She said, “If I were a parent, I wouldn't do anything different now, except I would say, "Geez, they're really starting to understand there are different kinds of ADHD."
“ADHD is really complicated. There are very likely several different subgroups of the disorder. Maybe in five years, we might have a test based on this. Then we would be able to know, are kids going to grow out of it or not? But parents shouldn't rush to pay to get a scan of their kid. It won't tell us anything now.”

From http://health.usnews.com
Margo Richter
December 9, 2007

Posted by margo at 10:39 AM | Comments (0)