White matter diminished in ASD teens born premature

In adolescents and young adults who screen positive for autism spectrum disorder (ASD), magnetic resonance imaging (MRI) reveals strong reductions in white matter, a new study has found.

Researchers conducted a prospective cohort study of 30 infants born extremely or very preterm. Participants were evaluated at a median age of 16.5 years, at which point 33 percent (n=10) had already been screened to have ASD, using the Social Communication Questionnaire and the Social Responsiveness Scale.

Abnormalities in MRI during infancy were more commonly detected in participants who eventually screened positive for ASD, though this effect fell short of statistical significance in logistic regression analysis (risk ratio [RR], 1.17, 95 percent confidence interval [CI], 0.68–2.0). None had hydrocephalus at birth.

Follow-up MRI showed similar results, with ASD participants showing significantly more abnormalities than comparators (RR, 4, 95 percent CI, 1.29–12.40). Of note, all abnormal scans showed diminished supratentorial white matter volume. Along with reduced white matter, two ASD participants also had smaller cerebellar volume.

Meanwhile, there were no signs of periventricular signal abnormalities, gliosis, or cortical or deep grey abnormalities. Of note, there were no ASD participants who had normal neonatal and follow-up MRI scans.

Decreased white matter volume during adolescence was associated with a tenfold increase in the odds of ASD (odds ratio, 10, 95 percent CI, 1.56–64.20; p=0.015).

“Given the selective vulnerability of the preterm white matter, the preterm population provides a unique window to further study the relationship between white matter development and ASD,” the researchers said.