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Landmark Study Sheds Light on Brain Development in
Healthy Children
05/26/2007 08:36 AM
www.medscape.com
NOTE: To view the article with Web enhancements, go to:
http://www.medscape.com/viewarticle/556968
Marlene Busko
Medscape Medical News 2007. © 2007 Medscape
May 18, 2007 — The first report from the National Institute of Health (NIH)
Magnetic Resonance Imaging (MRI) Study
of Normal Brain Development trial provides a glimpse into the brain performance
of healthy children and shows how
this is affected by sex, income, and age.
The findings are published online May 18 in the Journal of the International
Neuropsychological Society.
"In some ways [this database] is a tool, just like the human genome project, and
so I think this project is going to give
researchers tools that will really advance the field in ways that we can't even
imagine," lead author Deborah P. Waber,
PhD, from the Children's Hospital Boston, in Massachusetts, told Medscape.
Longitudinal Study of Population-Based Sample
The goal of the NIH MRI Study of Normal Brain Development was to create a public
database of imaging and
neuropsychological data from the normal healthy developing brain from birth to
young adulthood.
Participants were selected so that they were representative of the demographic
diversity (race/ethnicity and income) of
the US population in 2000, said Dr. Weber, adding that until now, researchers
relied on samples of convenience. More
than 35,000 families were targeted, and from these, 385 healthy children aged 6
to 18 years were enrolled at 6
pediatric centers in US cities. The children are being evaluated at 3 time
points: at baseline and 2 and 4 years later.
The children underwent imaging tests and standard tests to assess intelligence,
processing speed, verbal memory,
verbal fluency, spatial memory, fine-motor dexterity, handedness, executive
functions, academic skills (reading and
calculating), and psychosocial function. The effects of sex, age, and income on
task performance were determined.
This article describes the results of the neuropsychological evaluation of the
children at baseline.
High-Performing Group, Less Dramatic Sex and Income Differences
"Not surprisingly, these children consistently outperformed published norms,"
the group writes, adding that this is likely
due to the strict exclusion criteria for this study.
Girls performed better at tasks requiring processing speed and motor dexterity,
and boys were better at perceptual
analysis. Girls also tested better in verbal learning, but surprisingly, their
performance declined through adolescence.
http://www.medscape.com/viewarticle/556968_print Page 1 of 2
Landmark Study Sheds Light on Brain Development in Healthy Children 05/26/2007
08:36 AM
There were no sex differences in calculation ability.
As expected, the low-income children had lower IQ scores, but the group
outperformed population norms. Although
the low-income children scored lower on tests of reading comprehension and
calculation, they performed better than
expected in single-word reading. This suggests that tasks that require greater
integration of cognitive abilities (such as
reading) are more vulnerable to poverty-related factors than are basic skills
(such as single-word reading), the authors
write.
Dr. Waber observed: "One of the things that stood out for me is that the
differences according to income level were
less dramatic than they sometimes are in other studies." She added that the
participants were required to have no
psychiatric, neurologic, or developmental problems, or any family history of
these and no exposure to toxins, so not
surprisingly, more potential low-income than high-income participants were
excluded. A lot of cognitive differences that
investigators have reported for low-income children may be due to health
disparities that affect brain development, she
noted.
Proficiency for most tasks improved dramatically between age 6 and 10 years and
then leveled off during early
adolescence (age 10 to 12 years), suggesting that children approach adult levels
of ability to perform many
neurocognitive tests. These preliminary findings are based on a single point in
time and are averages of the
performance of a whole population, so they cannot measure changes that continue
to occur in adolescence, the
authors caution. Longitudinal data from the second and third visits will provide
more insight.
"This database will serve as an invaluable public resource for investigators for
many years to come," the authors
conclude. Dr. Waber added that this database provides "a benchmark of what a
healthy brain will look like — both
anatomically and in terms of function."
The study was funded by the National Institute of Neurological Disorders and
Stroke, the National Institute of Mental
Health, the National Institute of Child Health and Human Development, and the
National Institute on Drug Abuse.
J Int Neuropsychol Soc. 2007. Published online May 18, 2007.
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