Babies born prematurely are much more likely than other children to develop autism, ADHD and emotional disorders. Now researchers think they may have an idea about how that could happen.
There's evidence that preemies are born with weak connections in some critical brain networks, including those involved in focus, social interactions, and emotional processing, researchers reported at the Society for Neuroscience meeting in Chicago.
A study comparing MRI scans of the brains of 58 full-term babies with those of 76 babies born at least 10 weeks early found that "preterm infants indeed have abnormal structural brain connections," says Cynthia Rogers, an assistant professor of psychiatry at Washington University School of Medicine in St. Louis.
"We were really interested that the tracts that we know connect areas that are involved in attention and emotional networks were heavily affected," Rogers says. That would make it harder for these brain areas to work together to focus on a goal or read social cues or regulate emotions, she says.
The team used two different types of MRI to study the nerve fibers that carry signals from one part of the brain to another and measure how well different areas of the brain are communicating. Full-term infants were scanned shortly after they were born, while premature infants were scanned near their expected due date.
The researchers are continuing to monitor the brains of the children in their study to see which ones actually develop disorders.
Another team attending the neuroscience meeting presented evidence that at least some of the brain connection differences found in preemies at birth are also present during pregnancy.
The team used new MRI technology that allowed them to study the brains of 36 fetuses during the 30th week of pregnancy. Half the fetuses went on to be delivered prematurely and half went to full term.
When the researchers looked at connections between areas of the brain involved in movement and balance, the full-term fetuses had "higher levels of connectivity than the preterm born," says Moriah Thomason, an assistant professor in the Department of Pediatrics from Wayne State University School of Medicine in Detroit. This could explain why premature babies often are late to sit up and stand, she says.
The results suggest that it's not necessarily premature birth itself causing brain connection problems, Thomason says. Both premature birth and weak brain connections, she says, may be triggered by factors like stress or illness or exposure to toxins.
The new research does a good job revealing a problem in premature brains, says Jay Giedd, a professor of psychiatry at the University of California, San Diego who was not involved in either study. Now, he says, scientists and doctors will have to find a solution.
"The trouble is we really don't know how to change the connections very well," he says. "Can we do it with video games, exercise, meditation, yoga, diet?"
Ultimately, Giedd says, it's likely that repair work on the faulty brain circuits associated with prematurity should begin well before a child is born. It may be possible to stimulate developing brain circuits in utero with sound or something more invasive.
AUDIE CORNISH, HOST:
Babies born prematurely are three times more likely than other children to develop autism, ADHD and emotional disorders. now researchers think they may understand why. They found evidence that preemies are born with weak connections in some critical brain networks. NPR's Jon Hamilton sent this report from the Society of Neuroscience meeting in Chicago.
JON HAMILTON, BYLINE: Researchers from Washington University in St. Louis suspected that the brains of premature infants were different from birth, so the team used two forms of MRI to compare the brains of 58 full-term babies with those of 76 babies born at least 10 weeks early. Cynthia Rogers, a child psychiatrist, told reporters the full-term babies were scanned as soon after they were born while the premature babies were scanned at their expected due date.
CYNTHIA ROGERS: And what we found was that preterm infants indeed have abnormal structural brain connections.
HAMILTON: Rogers says the team focused on the bundles of nerve fibers, or tracts, that connect areas of the brain thought to be involved in ADHD, autism and emotional disorders.
ROGERS: We were really interested that the tracts that we know connect areas that are involved in attention and emotional networks were heavily affected in preterm children.
HAMILTON: Weak connections make it harder for these brain areas to work together to focus on a goal or read social cues or regulate emotions. Rogers says the team plans to continue monitoring the brains of the children in the study to see which ones actually develop disorders. Another team attending the neuroscience meeting wanted to know whether the brain differences in preemies are present in the womb. Moriah Thomason from Wayne State University in Detroit said new MRI technology gave the team a way to safely answer the question.
MORIAH THOMASON: And the way that we do this is we invite women that are pregnant to come in for an MRI, and the MRI is focused on the brain of the developing fetus.
HAMILTON: The teams scanned the fetuses of 36 women during the 30th week of pregnancy. Half the women went on to deliver prematurely and half had full-term babies. Thomason says the team focused on fibers that connect the two halves of the brain, and the results were clear.
THOMASON: Term fetuses had higher levels of connectivity than the preterm-born. So this really fits nicely with what we've seen in neonates and infants, really saying that already, these systems, prior to birth, are showing some of these differences.
HAMILTON: So what this most recent study is suggesting is that it's not premature birth itself causing the brain problems, but the problems may come from the same factors - like stress or illness - that contribute to a baby being born prematurely. Jay Giedd, a child psychiatrist from the University of California, San Diego, says the new research does a good job revealing the problem in premature brains. The trick, he says, will be to find a solution.
JAY GIEDD: The trouble is we don't really know how to change the connections very well. Can we can do it with videogames, exercise, meditation, yoga, diet? So a lot of ideas, but what actually tweaks these circuit formations for good or ill?
HAMILTON: And Giedd says ultimately, repair work on those faulty brain circuits should begin before a child is born. Jon Hamilton, NPR news, Chicago. Transcript provided by NPR, Copyright NPR.