Turning ADHD on Its Head
The researchers labeled the brain transmitter chemical dopamine, which is associated with movement, thought, motivation, and pleasure. They found that ADHD sufferers had 70% more dopamine transporters than the healthy controls. The scientists could not tell if that was a cause or an effect of the disorder.
To Wilens this builds on other studies showing similar distinctions in the brains of those with and without ADHD. He does note that the study only involved six patients, and it is preliminary in nature. He also pointed out that it shows that there is, indeed, an adult form of the disorder.
"One of the interesting things about this disorder is that there is good continuity between the childhood and adult forms of the disorder," says Wilens. "There is more and more evidence that ADHD in adults is a persistent form of the disorder."
Brown agrees, although he sees late recognition of the disorder as another consideration. What professionals are realizing now is that ADHD might not be recognizable in some cases until the child gets older and out of the more structured environments of grade school. Dealing with more complex tasks, different teachers, and moving from class to class may all combine to overwhelm those who had been doing well earlier.
The similarities between ADHD in adults and children in their symptoms and response to medications may help speed up investigation of treatment possibilities. Wilens notes that testing new medications on adults is easier and has less ethical baggage than testing them on children.
Brown says that the brain scan studies are one of the more dramatic pieces of research that are helping to document that there are differences in the way the brain chemistry operates in those with ADHD. However, he is also impressed by the genetic studies that document the degree to which it runs in families. The combined effect of these is that we are dealing with a biologically based disorder that in the past has been looked at as just "bad" behavior.
"The biggest shift in our understanding of this disorder is moving from thinking about it as a disruptive behavior disorder to the recognition that it is an impairment of the executive functions of the brain," says Brown. "Those are the areas that manage and integrate other functions in the brain and involve the ability to organize. It affects a person's ability to get organized and started on tasks."