Written by Honor Whiteman
Infants born preterm are known to be at greater risk for neurodevelopmental disorders. Now, a new study by researchers from King's College London in the UK brings us closer to understanding why - premature birth reduces connectivity in brain regions linked to cognitive functioning.
First author Dr. Hilary Toulmin, of the Centre for the Developing Brain at King's College, and colleagues publish their findings in the Proceedings of the National Academy of Sciences.
Preterm birth - defined as the birth of an infant before 37 weeks gestation - affected more than 450,000 babies in the US in 2012.
It is a leading cause of neurological disability among children in the US. Babies born preterm are at higher risk of cerebral palsy, autism and attention-deficit hyperactivity disorder (ADHD), among other intellectual and developmental conditions.
For their study, Dr. Toulmin and colleagues set out to gain a better understanding of the brain connectivity among babies born preterm in an attempt to uncover clues as to why preterm babies are more likely to develop neurodevelopmental problems.
The researchers used functional magnetic resonance imaging (fMRI) to analyze the connectivity between two specific brain regions - the thalamus and the cortex - among 66 infants. Of these, 47 were born prior to 33 weeks gestation and 19 were born at full term - between 37 and 42 weeks gestation.
The team says they focused on the connectivity between the thalamus and the cortex because these are the brain connections that develop quickly during preterm infants' care in neonatal units.
Preemies showed reduced connectivity in brain area linked to higher cognitive functioning
Among the babies born at full term, the researchers found the connectivity between the thalamus and the cortex was very similar to that of adults, which the researchers say supports previous findings that infants are born with mature brain connections.
Among the preterm infants, however, the team identified reduced connectivity between areas of the thalamus and areas of the cortex associated with higher cognitive function. This may explain why preterm babies are at greater risk of neurodevelopmental problems later in childhood, say the researchers.
What is more, brain scans of the preterm infants revealed increased connectivity between the thalamus and an area of the primary sensory cortex that plays a role in processing signals from the face, lips, jaw, tongue and throat.
Preterm infants' earlier exposure to breastfeeding and bottle feeding may explain this finding, according to the team.
The team says the earlier a preterm baby was born, the more pronounced the differences were in brain connectivity.
Overall, the team believes their findings bring us a step closer to understanding why infants born preterm are at higher risk of neurodevelopmental problems.
Senior author Prof. David Edwards, also of the Centre for the Developing Brain at King's College, says modern science has allowed the team to assess brain connectivity among preterm infants - something he says would have been "inconceivable" only a few years ago.
"We are now able to observe brain development in babies as they grow, and this is likely to produce remarkable benefits for medicine," he adds.
Dr. Toulmin says the next steps from this research will be to gain a better understanding of how their findings are associated with learning and developmental problems among preterm children as they get older.