Medical professionals are studying the link between serious infections and autism
If pregnant women develop a serious infection during their pregnancy that requires hospitalization for treatment, this increases the child's risk of developing autism.
Scientists from the internationally recognized Massachusetts Institute of Technology (MIT) and the University of Massachusetts Medical School found that serious maternal infections during pregnancy lead to an increased risk of developing autism in their children. The doctors released a press release on the results of their study.
Infections of the pregnant mother can cause brain changes in the child
In a study on mice, the experts found that infections can affect the composition of bacterial populations in the mother's digestive tract. In their study, the scientists wanted to find out whether a maternal infection during pregnancy leads to autistic-like behaviors in their offspring. They also discovered specific brain changes that produce such behaviors.
Scientists identify the region of the brain that is involved in autistic-like behaviors
“We were able to identify a region of the brain that is involved in all behaviors associated with this disorder,” explains author Professor Gloria Choi. If these results are confirmed in human studies, the findings could provide a clue to reduce the risk of autism. This would include blocking the function of certain strains of bacteria in the maternal intestine, the scientists explain.
How do infections affect the child during pregnancy?
A 2010 study that included all Denmark-born children born between 1980 and 2005 found that severe viral infections during the first trimester of pregnancy resulted in a three-fold increase in the risk of autism. Severe bacterial infections in the second trimester were also linked to a 1.42-fold increase in risk. The affected infections included influenza, viral gastroenteritis and severe urinary tract infections, the experts add.
Special immune cells are involved in the increased risk
Similar effects were also found in experiments on mice. A special kind of immune cells (so-called Th17 cells) and their effector molecule IL-17 are responsible for these effects. IL-17 then interacts with receptors found on the brain cells of the developing fetus. This leads to irregularities in certain parts of the cortex. In the current investigation, the doctors tried to find out more about these irregularities. So they wanted to determine whether the irregularities are responsible for the behavioral abnormalities that were found in the affected mice. The scientists found that the irregularities occur in a part of the brain called S1DZ. The irregularities reduce the populations of cells, which are also called interneurons.
Physicians were able to reverse behavioral abnormalities
When the researchers restored normal brain activity in this area, they were able to reverse the behavioral abnormalities that occurred. They were also able to induce behavioral abnormalities in otherwise normal mice by strongly stimulating the neurons in the SIDZ area. The S1DZ region sent messages to two other brain regions, which are known as the so-called temporal association area of the cortex and the striatum. If the researchers inhibited the neurons associated with the temporal association area, they could reverse social deficits that occurred. By inhibiting the neutrons associated with the striatum, they were able to end repetitive behavior.
Inflammation during pregnancy is just one reason for behavioral abnormalities
Not all mothers who experience a severe infection have a child with autism, and not all mice attempting behavioral disorders developed with inflammation. This suggests that inflammation during pregnancy is just one factor in behavioral disorders. The data from the study show that only the offspring of mice with a certain type of harmless bacteria developed behavioral disorders and irregularities in parts of the cortex. When the researchers killed these bacteria with antibiotics, the mice gave birth to normal offspring. These data suggest that only certain mothers who have these types of Th17 cell-inducing bacteria in their intestines may be susceptible to this inflammation-induced disease. (as)