|NIH Study Tracks Brain Development in Some 500
Children across U.S.
First Report Looks at Intelligence, Behaviors
from Ages 6-18
Children appear to approach adult levels of performance on many
basic cognitive and motor skills by age 11 or 12, according to
a new study coordinated by the National Institutes of Health (NIH).
The NIH Magnetic Resonance Imaging (MRI) Study of Normal Brain
Development is tracking brain and behavioral development in about
500 healthy American children, from birth to age 18. A report published
online today by the Journal of the International Neuropsychological
Society* contains the first glimpse of
behavioral data — covering IQ, motor dexterity, language,
computation, and social skills — collected from children
ages 6 to 18.
The study "will provide researchers with a reference point for
how the normal brain develops, so that they can better understand
what goes wrong in children who have brain abnormalities caused
by genetic disease, prenatal exposure to alcohol or drugs, or other
factors," said lead author Deborah Waber, Ph.D., an Associate Professor
of Psychiatry at Children's Hospital Boston and Harvard Medical
Some of the behavioral data validate trends seen in other studies;
for example, they show that family income has an impact on a child's
IQ and social behaviors. But the lack of evidence for dramatic
cognitive growth during adolescence was a surprise.
The long-term goal of the study team is to link these behavioral
data to MRI scans of the children's brains. Together, the two data
sets will allow researchers to view how the brain grows and reorganizes
itself throughout childhood, and to explore the meaning of the
structural changes they see.
"This study will provide a comprehensive database for clinicians
and scientists alike," said NIH Director Elias A. Zerhouni, M.D. "A
neurologist who notices something unusual in a child's MRI could
use the database to help determine if the anomaly is within the
normal range of variation, or if it is cause for concern. A researcher
studying an environmental toxin or genetic disease that affects
brain development could use the database to help determine where
and when development has strayed from its normal course."
The study was launched in 1999 in a joint effort by the National
Institute of Neurological Disorders and Stroke (NINDS), the National
Institute of Child Health and Human Development (NICHD), the National
Institute on Drug Abuse (NIDA), and the National Institute of Mental
Health (NIMH). The NIH Blueprint for Neuroscience Research, an
initiative that combines resources from those Institutes and other
NIH components, recently provided additional funding so that the
study team could collect brain scans by diffusion tensor imaging
(DTI), a kind of MRI. While conventional MRI allows clinicians
and researchers to visualize different parts of the brain, DTI
allows them to see the networks of fibers that connect these parts.
To peer into the normal developing brain, the investigators sought
children from diverse geographic, socioeconomic and ethnic backgrounds.
They recruited children from six sites across the U.S.: Children's
Hospital in Boston; Children's Hospital Medical Center in Cincinnati;
Children's Hospital in Philadelphia; University of California at
Los Angeles; University of Texas, Houston; and Washington University,
St. Louis. They also shaped the demographics of the study group — in
terms of family income and ethnicity — to resemble the demographics
of the U.S. population, based on census data from 2000. Finally,
they used questionnaires to exclude children who had any signs
or known risk of serious neurological or psychiatric disorders.
Recruitment and screening were handled by a Clinical Coordinating
Center at Washington University. A Data Coordinating Center at
the Montreal Neurological Institute at McGill University in Quebec
is overseeing the imaging arm of the study and building the database
of brain-behavior information.
Though no child will be observed for the entire 18-year developmental
span covered by the study, each one will be evaluated for several
months to several years, depending on their age. Children under
age 6 at the time of recruitment are expected to go through dramatic,
rapid developmental changes, and are being evaluated at short intervals.
A total of 385 children have been recruited within the 6-18 age
range, and are being evaluated at three time points — at
the beginning, middle and end of a four-year period.
Today's publication summarizes the results of psychological tests
conducted at the first time point. The tests measure a broad spectrum
of abilities, from fine motor control, to social skills, to aspects
of intelligence, such as the ability to explain verbal concepts
or solve visual puzzles.
Children from low income families performed somewhat more poorly
on IQ and achievement tests and displayed more behavioral problems
compared to children from middle and higher income families. They
did not differ, however, on many other measures of basic cognitive
functions, like memory and verbal fluency, or on most measures
of social adjustment. A relatively larger percentage of low income
children were excluded by the study's rigorous selection criteria,
but the healthy low income children who did participate performed
above published norms for their demographic. This suggests that
in previous studies, general health disparities might have inflated
the cognitive gap between low and high income children, Dr. Waber
There were hints of much-cited differences in verbal and spatial
ability between boys and girls, but these differences were not
as sharp as those described in previous reports. In fact, there
were no sex differences in verbal fluency. There were also no differences
in calculation ability, suggesting that boys and girls have an
equal aptitude for math.
Regardless of income or sex, children appeared to improve rapidly
on many tasks between ages 6 and 10, with much less dramatic cognitive
growth in adolescence. This result fits with previous research
suggesting that in adolescence, there is a shift toward integrating
what one knows rather than learning new basic skills. Dr. Waber
cautions, however, that these data provide "snapshots" of development
in different children at different time points, rather than following
each child over a series of time points.
“We don’t know whether every child’s performance slows during
adolescence, or whether some children continue to improve, while
others do not," Dr. Waber said. "It's also possible that our standard
tests don’t measure what really changes in adolescence. As we follow
these children over time, we will have a better understanding of
is the nation’s primary supporter of biomedical research on the
brain and nervous system. NICHD (http://www.nichd.nih.gov/)
sponsors research on development, before and after birth; maternal,
child, and family health; reproductive biology and population issues;
and medical rehabilitation. The mission of NIMH (http://www.nimh.nih.gov/)
is to reduce the burden of mental and behavioral disorders through
research on mind, brain, and behavior. NIDA (http://www.nida.nih.gov/)
supports most of the world's research on the health aspects of
drug abuse and addiction, and carries out a large variety of research
programs to inform policy and improve practice.
The National Institutes of Health (NIH) — The Nation's
Medical Research Agency — includes 27 Institutes and
Centers and is a component of the U.S. Department of Health and
Human Services. It is the primary federal agency for conducting
and supporting basic, clinical and translational medical research,
and it investigates the causes, treatments, and cures for both
common and rare diseases. For more information about NIH and
its programs, visit www.nih.gov.