Brains of human fetuses in the womb have been scanned by researchers for the first time to observe the impact of maternal alcohol consumption on prenatal neural development. Results revealed that alcohol exposure leads to significant structural changes within key brain regions including the hippocampus and the germinal matrix, which is where brain cells are generated during early fetal growth.
Several postnatal studies have indicated that babies with fetal alcohol spectrum disorders – resulting from alcohol use during pregnancy – tend to have enlarged hippocampi. As the hippocampus has a central role in learning, memory, and emotional regulation, it is unsurprising that children with these conditions often have learning disabilities or behavioral problems.
However, until now, scientists had never pinpointed the beginnings of these structural abnormalities, as the early brain development of fetuses exposed to alcohol had not been observed. To shed some light on the matter, a team of researchers from the Medical University of Vienna used functional magnetic resonance imaging (fMRI) to scan the brains of 27 fetuses aged between 20 and 37 weeks that had been exposed to alcohol, plus 36 controls that had not been exposed to alcohol.
Presenting their research at the annual meeting of the Radiological Society of North America, the researchers explained how they analyzed the total volume of 12 different brain regions, painting a picture of alcohol's effect on different areas of the fetal brain. Results indicated that alcohol-exposed fetuses had larger hippocampi than controls, while the corpus callosum – which connects the two hemispheres of the brain – was also enlarged.
The alteration of the corpus callosum may explain why fetal alcohol spectrum disorders are associated with structural abnormalities in both hemispheres – although the researchers were intrigued to find an enlargement of this brain structure in the fetuses, as infants with these disorders usually display a reduction in the thickness of the corpus callosum.
Compared to controls, fetuses that had been exposed to alcohol also showed decreases in volume within the periventricular zone and germinal matrix. During early fetal development, all neurons are generated within the germinal matrix and migrate to other parts of the brain, so a thinning of this key structure is an alarming finding.
Summing up the relevance of this work, study author Gregor Kasprian explained in a statement that he and his colleagues “wanted to see how early it’s possible to find changes in the fetal brain as a result of alcohol exposure.” While more research is needed in order to tease out the full implications of the team’s findings, the scans lay bare the fact that “alcohol exposure during pregnancy puts the brain on a path of development that diverges from a normal trajectory.”