Preemies With Faster Brain Growth May End Up Smarter

British study found growth rate of the cortex predicted scores on intelligence tests

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WEDNESDAY, Oct. 12 (HealthDay News) -- Growth in a particular part of a premature baby's brain in the first weeks and months following birth may predict how well a youngster is able to think, plan and pay attention later in childhood, new research suggests.

In a study published in the Oct. 12 issue of Neurology, British researchers used MRI to measure the brains of 82 premature infants born before 30 weeks -- well ahead of the typical 40-plus weeks a normal pregnancy involves.

In the study, MRI measured an area of the brain called the cerebral cortex, the outer layer of "gray matter" that looks like deep folds and wrinkles, and which covers the cerebrum. It is responsible for a variety of functions including memory, attention and language. Scientists believe the winding outer covering's structural complexity, also referred to as the "cortical ribbon" -- not just brain volume -- is a key to intelligence.

Brain images were taken during the early weeks and months that followed the premature births -- the time frame during which the babies would have been carried by the mother if born full-term. Later, at age 2, and again at age 6, the children were given intelligence and developmental tests.

The greater the cerebral cortex growth was in early life, the better the child performed complex tasks at age 6, said study author Dr. David Edwards, a professor of neonatal medicine and director of the Centre for the Developing Brain at Imperial College, in London.

"The period before normal-term delivery is critical for the growth of the brain in quite specific ways, and if this is disrupted by being born too early, it affects long-term cognitive abilities," Edwards explained.

Edwards said a 5 percent to 10 percent reduction in the surface area of the cerebral cortex at full-term age predicted a lower score on intelligence tests at age 6. However, he noted that a child's motor skills were not linked with the rate of cerebral cortex growth, and overall brain size was not connected to general cognitive ability either.

The research has merits, said Dr. Peter Rosenberger, a developmental neurologist who wrote an accompanying editorial.

"What the study helps confirm is that it is not the size of the brain that matters, but rather its complexity, which the authors have defined as number of folds or convolutions per unit of brain mass. What we don't know yet is what this greater complexity confers upon the brain," said Rosenberger, formerly director of the Learning Disorders Unit at Massachusetts General Hospital, currently in private practice in Boston.

Because there was no group of full-term babies to compare the premature infants with, the study reveals little about brain development in babies born early, said Rosenberger.

In his editorial, Rosenberger said the authors' frequent references to "rate of growth" are somewhat misleading, and he noted that nearly 30 percent of the infants were only scanned one time, which doesn't allow for tracking a growth rate.

"The results are not a huge surprise," said Dr. Judy Bernbaum, medical director of the neonatal follow-up program at The Children's Hospital of Philadelphia. She agreed with Rosenberger's editorial: "It helps to confirm that the better developed your brain is early on, the more likely you're going to do better from a developmental standpoint later on."

Bernbaum said parents of preemies with lower brain volume shouldn't worry, though. "Brain growth goes on for a couple of years. Even if at birth you have low brain volume, you still have a lot of potential you can maximize," she said.

Good nutrition in the first two years of life, a healthy and low-stress home environment and stimulation from parents and caretakers all contribute to the growth of the brain, Bernbaum said.

The study doesn't provide answers to how to boost your baby's brain, however.

"For the public, they are always eager to know what can I do? But we don't really have a handle on it here.

This is not a study demonstrating the effect of an intervention," said Raman Sankar, chief of pediatric neurology at Mattel Children's Hospital at the University of California, Los Angeles. But, Sankar said, "people with preemies can go to development centers and get a lot of therapy. It can't hurt and probably helps."

Building a healthy brain can begin well before birth, too, Bernbaum added. Pregnant women who take a prenatal vitamin, eat a well-balanced diet low in salt and fat, and rich in calcium and protein, are giving their children, even babies born prematurely, the best odds, Bernbaum said.

SOURCES: David Edwards, D.Sc., professor, neonatal medicine, director, Centre for the Developing Brain, Imperial College, London; Peter Rosenberger, M.D., former director, learning disorders unit, Massachusetts General Hospital, in Boston; Judy Bernbaum, M.D., medical director, neonatal follow-up program, The Children's Hospital of Philadelphia; Raman Sankar, M.D., chief, pediatric neurology, Mattel Children's Hospital, University of California, Los Angeles, Oct. 12, 2011, Neurology

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