A new study has divided premature babies into three groups based on their scores on tests that measure cognition and behavior, and has found that some premature babies score higher than average. The new classifications offer hope for earlier diagnoses of conditions such as attention deficit hyperactivity disorder (ADHD).
Premature birth
About 13 million babies are born prematurely each year, and preterm birth is associated with an increased risk of attention deficit hyperactivity disorder, problems with social development, and lower grades.
However, the problem with preterm analyses is that they do not take into account the diversity that exists among babies born preterm, some of whom have better outcomes than the average for babies born at term. Preterm birth refers to birth before 37 weeks of gestation, while 40 weeks is considered full term.
Grouping premature babies into one group tends to hamper efforts to personalize care for each child, according to researchers. Now, the new study, published Aug. 13 in the journal Child Development, finds that premature babies fall into three profiles, with significantly different scores on tests that measure cognition (thinking, reasoning, and remembering) and behavior (the ability to pay attention).
Academic performance
The study, conducted by researchers from New York University School of Medicine, identified the first neurocognitive profile, which included 19.7 percent of all children tested, as showing above-average performance even for children born at term on standard cognitive tests. The second profile, which represented 41 percent of children, showed above-average scores on four tests (such as memory, vocabulary, and reading) and below-average scores on three others (pattern recognition and working memory).
The third file (39.3%) recorded below average results on all tests, and the cognitive deficits observed in this group were associated with attention deficits and lower grades in school. In particular, children born prematurely in the first file scored 21% higher on average on standard cognitive tests than those in the third file. In behavioral tests, 2.5% of children in the first file were found to have attention deficits compared to 9.9% in the third file.
As for academic performance, 66.47% of students in the first file had a grade point average of (A-) or higher, 60.69% in the second group, and 32.21% in the third file.
“Our study debunks the idea that every child born prematurely is born with cognitive and behavioral defects,” says lead author Dr. Iris Mino, a postdoctoral researcher in the lab of Dr. Moriah Thomasson, vice chair of research in the Department of Child and Adolescent Psychiatry.
“Precision medicine is not based on a general diagnosis, because two patients may have the same diagnosis, such as preterm birth, but their experiences may be very different,” added Thomasson, the study’s lead author. “Our study highlights the complexity of preterm birth and holds promise for improving treatment for each individual child.”
the study
The current study analyzed cognitive and behavioral data from 1,891 boys and girls born prematurely, ages 9 to 11, who were enrolled in another large, ongoing study: the Adolescent Brain Cognitive Development Study. This study tracks cognition in each child using a standardized battery of seven tests that measure attention, decision-making, memory, reading comprehension, and processing speed. The researchers then used a statistical technique to sort each child’s scores into previously hidden subgroups that better represent the children’s development.
brain differences
Neuroimaging of each child showed that the 9- to 11-year-olds in the third file had brains that were 3% smaller in volume and gray matter surface area than the children in the first file. While the children in the third file were born 4.5 days earlier than the other files, the smaller brain volumes were not related to the extent of prematurity.
The authors believe that the question of whether what Some of the differences in outcomes between children may be related to smaller brain size and deserve further investigation, along with their causes.
The research team also studied functional connectivity, which measures activity levels in two interconnected brain circuits by measuring blood flow to them using functional magnetic resonance imaging.
The connectivity between the dorsal attention network, which is involved in directing and maintaining attention toward relevant external information, including that processed by the visual network, and the default network, which may be active during periods of self-directed thought or self-reflection, was studied. The researchers found that the connectivity between them was 11.21% weaker in the third file compared to the first file.
Because the dorsal attention network is known to play a role in maintaining attention, the functional connectivity findings underscore the potential of the team’s approach for early identification of possible ADHD diagnoses, and for targeted behavioral and pharmacotherapy, the authors said.
Importantly, the team’s analyses also found that premature babies who were of African descent were nearly four times more likely to fall into the third low-performing profile.
Calls for care for premature babies
“Based on these findings, we call for social and structural interventions to ensure that all premature babies have equal access to care,” Mino said, according to EurekAlert. “Children who receive speech, physical and behavioral therapy almost daily, which is more likely to happen in wealthier families, tend to do better on school tests, but other factors are involved. For example, children in communities with more health insurance coverage were less likely to be in the third category.”
In the future, the research team plans to conduct further studies to determine what factors are common among premature babies who later perform poorly (for example, were these babies more likely to have suffered from oxygen deprivation during birth), as well as what factors helped the 20 percent of premature babies in the first file perform better than many full-term babies.