US News and World Report– May 2002
By Marianne Szegedy-Maszak
In the darkened office of Lexicor Health Systems in Boulder, Colo., 11-year-old Shannon closes her dark brown eyes and sits quietly in her chair. She is wearing a multicolored electrode-studded cap, which transmits the electrical impulses of her brain to an electroencephalogram, or EEG. Behind her on a computer screen scrawl 19 wild lines that represent the activity in several regions of her brain. One would never surmise from Shannon's Zen-like demeanor what the brain scan is detecting inside her head: that she is one of the more than 2 million children in America who suffer from attention deficit hyperactivity disorder.
The result of Shannon's session will be a QEEG–a "quantified EEG" that will allow diagnosticians to statistically compare her brain with thousands of others. What they are interested in, specifically, is the proportion of low-frequency theta brain waves to much faster beta waves in a region of the brain called the prefrontal cortex. Studies have suggested abnormalities in both these rhythms associated with attention–or lack of it. Children produce a lot of low-frequency theta brain rhythms when they struggle to concentrate, and when their concentration is overwhelmed by too much stimulation they produce the speedier beta waves. By comparing what Shannon's brain does with both "normal" brains and those of others who have been diagnosed with ADHD, researchers at Lexicor are hoping for the first time to provide a quantitative tool to help identify this vexing disorder.
Genetic mystery. The QEEG may never become the "gold standard" in diagnosing ADHD. But it illustrates how increasingly sophisticated understanding of brain activity may offer clinicians greater confidence in their diagnosis. It may also hold out promise for the 20 percent of children diagnosed with ADHD who do not respond to the usual stimulant treatment–by identifying a pool of symptoms that they all might share. Clearly, genes play a role in ADHD, because it runs strongly in families, but no ADHD gene has yet been identified. Lacking that kind of definitive diagnostic tool, a deeper understanding of the neurology underlying the disorder could help clinicians untangle true ADHD from accompanying disorders and disorders that resemble it. Indeed, QEEG is one of several brain-scanning technologies now being deployed to home in on the unique properties of the distracted mind.
Such objectivity would be a godsend for parents. "There is not a single test that we have, no rating scale, no brain scan, there is nothing that will tell you yes or no about ADHD," says Thomas Brown, associate director of the Yale Clinic for Attention and Related Disorders. That's because, like most mental disorders–depression, anxiety–attention disorder is a "spectrum diagnosis": Its widely varying symptoms are a challenge even to the most skilled clinician. Is this attention problem really disabling or merely within the parameters of "normal"? How do disorders like learning disabilities–which tend to accompany many ADHD diagnoses–compromise attention? And could the problem not be ADHD at all but what doctors call "mimics"? Mimics can be biological (sleep deprivation), psychological (anxiety or depression), or social (a child's response to poor parenting or teaching). Or is ADHD, as some critics contend, a culturally bound diagnosis of "boyhood"? "Lots of people confuse having the symptoms with having the disorder," says Mark Stein, the chief of psychology at the Children's National Medical Center in Washington, D.C.
Ritual Rx. As a girl, Shannon is outnumbered more than 2 to 1 by boys in having attention disorder. But her clinical journey has not been that different. In an office next door to Shannon's examination room, her mother pulls out a thick file. Over an inch of paperwork charts her daughter's trajectory from classrooms to doctors' offices to psychologists' offices. And she is actually one of the lucky ones. Some parents simply get first complaints and then testing reports from a teacher, and then turn to their pediatrician to fix the problem. The pediatrician typically decides to prescribe the stimulant medication Ritalin to see if the child responds–a practice as common as it is dangerous. "You don't want to make a diagnosis based solely on treatment response," says Lenard Adler, the director of the ADHD program at New York University.
Sometimes it's difficult to be confident in a diagnosis for a murky disorder. ADHD typically involves a triad of symptoms that are themselves subject to interpretation: the inability to sustain attention, difficulty in controlling impulsivity, and, sometimes, hyperactivity. According to the DSM-IV, the diagnostic bible of the American Psychiatric Association, symptoms can range from frequently losing things to persistent difficulty in completing tasks. Moreover, many children who have ADHD are not hyperactive at all. "In the past, parents and children were given a moral diagnosis," says Edward Hallowell, a Harvard psychiatrist and author of <I style="mso-bidi-font-style: normal">Driven to Distraction. "The child was seen as bad, stupid, wayward, weak, or the product of bad parenting. Now we know that powerful brains typically have powerful vulnerabilities and powerful strengths.''
Given the complexity of the brain's attention and thinking mechanisms, the prevalence of the disorder is not surprising. "There is so much complicated communication in the brain, with different parts talking to each other," says Timothy Wilens, a staff psychiatrist at Massachusetts General Hospital, "that it is not easy to get unification." For example, many studies suggest that the reduced frontal-lobe activity in ADHD may be caused in turn by decreased activity in the basal ganglia, a deeper part of the forebrain that generates two important neurotransmitters called dopamine and norepinephrine. Studies suggest that abnormally low supplies of these chemicals may be involved in inattention. Indeed, the theory behind stimulant medications is that they adhere to and activate these illusive neurotransmitters and, through a cascade of neuronal events, "light up" the prefrontal cortex.
Back in Boulder, her electrical beanie off, Shannon is playing on a computer. Her mother collects her files, anticipating that she will be able to confirm exactly what is going on in her daughter's brain. And in the process put her own mind at rest: "I ended up feeling as if the problem had to do with me as a parent,'' she says. "Now that we can quantify and seal the diagnosis, I feel more confident in what we can do about it."