Drinking alcohol during pregnancy can damage white matter in a fetus' frontal and occipital lobes, which play a major role in executive function and visual processing. The finding may help explain problems seen in infants whose mothers drink during pregnancy, a new study says.

"The brain's white matter is made up of nerve bundles that transfer information between brain regions," study corresponding author Susanna L. Fryer, a researcher at San Diego State University's Center for Behavioral Teratology, said in a news release.

"Optimal white-matter integrity is thought to support efficient cognition. So, the finding that prenatal alcohol exposure is associated with altered white-matter integrity may help explain aspects of the cognitive and behavioral problems that individuals with fetal alcohol spectrum disorders (FASDs) commonly face," she said.

In this study, Fryer and her colleagues used a type of MRI called diffusion tensor imaging (DTI) to assess white-matter microstructure in the brains of 27 young people, ages 8 to 18. Of those participants, 15 were born to mothers who drank heavily during pregnancy.

"The brains of individuals with FASDs showed evidence of altered nerve fiber integrity at a microstructural level, even though total brain size was statistically equivalent between alcohol-exposed and comparison participants," Fryer said.

"Also, within the alcohol-exposed group, we generally found that white-matter microstructure did not differ based on whether youth met criteria for a diagnosis of fetal alcohol syndrome (FAS). In other words, similar brain alterations and behavioral problems can occur because of prenatal alcohol exposure, with or without the facial features and physical growth insufficiency required to diagnose FAS."

The study was published online Dec. 19 and in the March print issue of the journal Alcoholism: Clinical and Experimental Research.