This post has been corrected. See note at bottom.
Subtle surface deformities in a deep brain region vital for movement and learning have been linked to risks for attention deficit and other disorders among premature infants, according to a new study.
The study for the first time mapped minute differences in specific areas of the putamen, a kind of crossroads deep in the brain’s architecture where signals, including sensation and motor function, coalesce and connect with higher regions associated with more complex functions.
Injuries and deformities to the putamen have been linked to deficits in attention-based learning and executive function – deciding on appropriate action – among adolescents who had been born prematurely, according to the study, published online Wednesday in the journal PLOS One.
“It’s sort of a pathway,” said USC clinical pediatrician Dr. Douglas Vanderbilt, an author of the study. “These sub-cortical structures are where sensation and motor functions coalesce before they go to the association cortex, which is the higher brain structures. They’re essential because they’re the freeways that connect to those downtown areas. So if there’s problems with that, information is not going to be delivered.”
Researchers compared magnetic resonance images from 17 infants born about one to three months prematurely with those of 19 infants born at full gestational age. The analysis, involving minuscule grids and complex mathematical models, showed differences in areas of the putamen that have been correlated with ADHD among older children, said lead author Natasha Lepore, a USC physicist and radiologist who spearheaded the analysis.
“We found that there’s one area in the surface of the putamen that’s different both in terms of surface area and thickness,” said Lepore, whose lab is at the Saban Research Institute at Children's Hospital Los Angeles. “The interesting part of it, to us, is this is exactly the same area that is different in children that have ADHD.”
Premature infants have about four times the rate of subsequent ADHD diagnoses as do children who were born at full gestational age, and are similarly susceptible to deficits in executive functioning, said Vanderbilt, who treats patients at CHLA.
Chiara Nosarti, a psychiatrist at Kings College, London, who was not involved in the study, said the USC approach was novel and could offer additional insights into mood disorders and psychosis among adolescents.
For clinicians such as Vanderbilt, who studies behavioral development, techniques used in the study could help diagnose disorders at younger ages, to help tailor earlier interventions. Most clinicians can’t reliably diagnose ADHD, based on behavior and observation, in children under about 4 years of age, largely because the disorder can be confused with other issues.
“I need techniques to be able to do more than make diagnoses that are based on subjective observations of teachers and parents, or what I see in the clinic,” Vanderbilt said. “I need biomarkers, and we don’t have those right now for ADHD, and we don’t really have that for executive functioning. This may be the technique.”
The brains of premature infants face a two-fold hazard: their brain development is interrupted, and they may suffer further injury as the body directs blood toward other underdeveloped and struggling organs that it deems more vital, Vanderbilt said.
The study focused exclusively on architecture – form, rather than function. But imaging that can capture real-time neuron activity has confirmed many of the anomalies found on surfaces or volumes of brain regions, Lepore said.
For his part, Vanderbilt likened the technique to a more reputable form of phrenology, a pseudoscience that attempted to discern brain activity and personality from the shape and size of people’s skull.
“In the past, you had physicians actually look at how the skull was shaped, for knots, and that’s called phrenology. This is phrenology 2.0,” Vanderbilt said. “This is actually looking at the brain structure on a very fine micro level and it telling us things.”
Other study authors were from Arizona State University, Children's Hospital of Pittsburgh and UCLA.
[Corrected at 5:34 p.m.: A previous version of this post attributed the study solely to USC. Though USC researchers had a major role in the study, several of the study's authors are affliated with other institutions, which have been identified in the updated post.]