Probing Question: Has there been an increase in ADHD?

Illustration by James Collins

By Joe Anuta
Research/Penn State

Attention Deficit Hyperactivity Disorder (ADHD), a neurological condition characterized by inattention, restlessness and impulsivity, commonly is diagnosed in early childhood and affects between 3 percent and 5 percent of American children, according to the National Institute of Mental Health. This means that "in a classroom of 25 to 30 children, it is likely that at least one of them will have ADHD."

Some studies -- and some school teachers -- will tell you that's a conservative estimate. Many believe that ADHD is on the rise, and the latest figures from the American Society of Pediatrics suggest that 12 percent of the nation's youth suffer from this disorder.

According to Jeanette Ramer, associate professor of pediatrics at the Penn State College of Medicine, there has been an increase in ADHD cases, but whether that means an actual rise in the number of children born with the condition or a perceived increase due to better recognition and more frequent diagnosis is not entirely clear. Ramer believes it's a little bit of both.

On the biological side, she said the disorder is genetic. "About half the time when we diagnose a child, a parent will also have it."

The brains of children with ADHD perform abnormally in two ways, indirectly observable by functional magnetic resonance imaging (fMRI). Primarily, their frontal lobes appear to have problems with regulation of dopamine, a type of brain chemical known as a neurotransmitter which is essential to smooth signaling between neurons and other cells. They also may show an imbalance of norepinephrine, another neurotransmitter that may regulate mood in addition to attention, Ramer said. "We don't have direct measurements of these imbalances, but currently people are medicating on this principle, and it seems to be working."

Complicating the biological component, however, are sociological factors. For example, the number of ADHD cases varies largely from region to region in America, Ramer said, suggesting that cultural norms influence diagnosis. "We're not seeing a true picture of the incidence." In central Pennsylvania, she noted, ADHD is "well-identified," but in other rural areas in America, as well as in most of Europe, the disorder is commonly dismissed "as simply a behavioral problem," which can trivialize the contributing neurological factors.

To further blur the picture, Ramer said that sociological conditions can expose the disorder where it might otherwise have remained hidden. "Chaotic households and a lack of a support system" can exacerbate ADHD symptoms, she said, and so can increasing demands at school. Children required to remain seated and complete ever-larger workloads "don't have the same opportunities to compensate that they may have had in years past."

Ramer is careful to distinguish childhood ADHD from a growing trend of adults being diagnosed with the disorder. The latter, she said, may be a fad. "It shouldn't appear de novo," which is to say that ADHD doesn't just pop up in adults who didn't suffer with it as children.

In these cases, she suspects, what's being labeled ADHD is the inevitable fall-out of an information-overload society -- or job-related stress. "If you’re asked to multi-task all the time, it promotes behaviors that can look similar to ADHD."

One way to help accurately diagnose an adult with the disorder, she said, is to require the patient's parents to complete questionnaires that evaluate characteristics of ADHD, recalling what their son or daughter was like at age 10.

For those who doubt the biological basis of true ADHD in children, however, she has a simple question: "If it were all behavioral, why would a child choose to be fidgety?"

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Jeanette C. Ramer is associate professor in the division of genetics, department of pediatrics, in the Penn State College of Medicine, Milton S. Hershey Medical Center. She can be reached at jcr2@psu.edu.

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