Study finds MRI reveals altered brain structure in foetuses exposed to alcohol

"Foetal alcohol syndrome is a worldwide problem in countries where alcohol is freely available," said Gregor Kasprian, M.D., associate professor of radiology at the Medical University of Vienna in Austria. "It's estimated that 9.8 per cent of all pregnant women are consuming alcohol during pregnancy, and that number is likely underestimated," he added.

Foetal alcohol syndrome is the most severe form of a group of conditions called foetal alcohol spectrum disorders that result from alcohol exposure during pregnancy. Babies born with foetal alcohol spectrum disorders may have specific physical features, learning disabilities, behavioural problems, or speech and language delays. According to Dr Kasprian, one in 70 pregnancies with alcohol exposure results in foetal alcohol syndrome. "There are many postnatal studies on infants exposed to alcohol," Dr Kasprian said.

"We wanted to see how early it's possible to find changes in the foetal brain as a result of alcohol exposure," he added. For the study, researchers recruited 500 pregnant women who were referred for a foetal MRI for clinical reasons. On an anonymous questionnaire, 51 of the women admitted to consuming alcohol during their pregnancy. The questionnaires used were the Pregnancy Risk Assessment Monitoring System (PRAMS), a surveillance project of the Centres for Disease Control and Prevention and health departments, and the T-ACE Screening Tool, a measurement tool of four questions that identify risk drinking.

"We provided a safe environment where women could feel comfortable honestly answering the questions," Dr Kasprian said. After eliminating some of the foetal MRIs for reasons such as structural brain anomalies and/or poor image quality, the final study group consisted of 26 foetal MRI exams from 24 alcohol-positive foetuses and a control group of 52 gender- and age-matched healthy foetuses. At the time of imaging, foetuses ranged in age between 20 and 37 weeks.

The researchers used super-resolution imaging, which allowed them to create one dataset to re-construct each foetal brain. Next, they completed an analysis of 12 different brain structures, computing total brain volume and segment volumes of specific brain compartments. "One of the main hallmarks of our study is that we investigated so many smaller sub-compartments of the brain," said co-author Marlene Stuempflen, M.D., scientific researcher at the Medical University of Vienna.

The statistical analysis revealed two major differences in the alcohol-exposed foetuses compared to healthy controls: an increased volume in the corpus callosum and a decreased volume in the periventricular zone. "This is the first time that a prenatal imaging study has been able to quantify these early alcohol-associated changes," Dr Stuempflen said.

The corpus callosum is the main connection between the brain's two hemispheres. Dr Stuempflen noted that it is fitting that this very central structure is affected, because the clinical symptoms of foetal alcohol spectrum disorders are highly heterogeneous, or diverse, and cannot be pinpointed to one specific substructure of the brain. "The changes found in the periventricular zone, where all neurons are born, also reflect a global effect on brain development and function," she said.

The researchers said that finding a thicker corpus callosum in the alcohol-positive foetuses was surprising because the corpus callosum is thinner in infants with foetal alcohol spectrum disorders. "It appears that alcohol exposure during pregnancy puts the brain on a path of development that diverges from a normal trajectory," Dr Kasprian said.

"Foetal MRI is a very powerful tool to characterize brain development not only in genetic conditions but also acquired conditions that result from exposure to toxic agents," he added. Additional co-authors were Ernst Schwartz, M.Sc., Mariana Diogo, M.D., Ph.D., Sarah Glatter, M.D., M.M.Sc., Birgit Pfeiler, Victor Schmidbauer, M.D., Lisa Bartha-Doering, Ph.D., Rainer Seidl, M.D., Elisabeth Krampl-Bettelheim, M.D., and Daniela Prayer, M.D.