~e; and now: electrical beanie hats
human being <firstname.lastname@example.org>
Thu, 2 May 2002 20:34:31 -0500
(thanks to * for the fwd)
Health & Medicine 5/6/02 :
The Mind Maze
Can 'distraction' be found in the brain's biochemistry?
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 atten- tion 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
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 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."
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