We Might Finally Know One of the Causes of Autism, Thanks to Science

expectant mom holding belly
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Doctors have known for a while that pregnant women who are hospitalized for infection are more likely to have a child who has autism. Now, two new studies from the University of Massachusetts and MIT shed light on why this happens and suggest women who carry a certain strain of gut bacteria are most at risk.

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Researchers at the University of Massachusetts released findings earlier this week that suggest that pregnant women's bodies could react to serious infections in ways that directly influence the brain development of their unborn children. In pregnant women, when the body is fighting extreme infections, the maternal immune activation (MIA) is triggered. It is this immune response that seems to be directly linked to an increased risk of autism. 

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Using pregnant mice, researchers were able to identify what part of the fetal brain is impacted by MIA and link those effects to a specific type of immune cell -- Th17, and an associated molecule called IL-17.

According to scientists, IL-17 interacts with receptors in the brain cells of a developing fetus, which, in turn, leads to major irregularities, or "patches," located in a part of the brain known as S1DZ, or the primary somatosensory cortex. In mice, these irregularities produced symptoms like repetitive actions and changes in sociability, similar to hallmark signs of autism observed in humans. 

The studies also probed the question of why not all pregnant women who develop severe infections end up having a child with autism. 

"This suggests that inflammation during pregnancy is just one of the factors," said Gloria Choi, a member of MIT's McGovern Institute for Brain Research, in an interview with MIT News. The research revealed that mice who carried a specific type of normally harmless bacteria in the gut were far more likely to have offspring with behavioral abnormalities.

"This data strongly suggests that perhaps certain mothers who happen to carry these types of Th17-inducing bacteria in their gut may be susceptible to this inflammation induced condition," said study coauthor Jun Huh to MIT news.

Ultimately, the study concluded that if a pregnant woman does face an infection serious enough to warrant hospitalization, it may be possible to use things like diet changes and antibiotics to dramatically reduce the effects of the infection on her unborn child.

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As groundbreaking as these studies are, even scientists are still wary of officially linking their results to the cause of autism in humans. After all, humans are not mice and there's a wealth of research that must be done before we can definitively say what causes autism in humans. Still, it certainly feels like a step in the right direction toward understanding not only autism, but a number of developmental changes that could be caused by major infections during pregnancy.

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