Teenagers who came into the world as “preemies” have altered brain connectivity on MRI, as well as differences in cognitive function, compared with their peers who spent the full nine months in utero.

The open-access journal PLOS One published the European study behind the findings, which largely confirm previous studies, online June 8.

A team led by Brigitte Vollmer, MD, PhD, of the Karolinska Institute in Sweden and the University of Southampton in the U.K. drew data from the Stockholm Neonatal Project, a longitudinal, population-based study of children born preterm (before reaching 36 weeks of gestation) with very low birth weight (less than 3.4 pounds) between 1988 and 1993.

They compared psychological assessments of general intelligence and executive function from 134 18-year-olds who were born prematurely with those from 94 full-term participants.

The researchers also looked at brain MRI scans of 71 preterm and 63 full-term participants ranging in age from 12 to 18 (mean age, 15.2 years). The scans included 3D T1-weighted images for volumetric analysis and diffusion tensor MRI for white matter microstructure.

Importantly, participants in the preterm group had been born at a weight appropriate to their gestational age and had no radiological signs of preterm brain injury on neuroimaging.

On analysis, Vollmer and colleagues found significant differences between the two groups in grey and white matter regional volumes as well as widespread differences in fractional anisotropy (a measure of white-matter microstructure).

They observed no significant correlations between cognitive measures and brain volumes in any group after correction for multiple comparisons. However, the prematurely born young people had significant correlations between neural-pathway disturbance on MRI and impaired cognitive function on psychological assessment.

There were no such correlations in the full-term group.

“Overall, our findings provide additional strong evidence that the observed differences in cognitive functioning between persons born preterm and those born at term are a consequence of widespread altered brain connectivity, still present many years after preterm birth,” the authors write in their discussion. “Furthermore, our findings also support the notion that preterm birth per se induces altered brain development, with long lasting anatomical and behavioral consequences.”

To read the full study report, click here.