Maternal Streptococcal Infection May Play Role in Autism Spectrum Disorder
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This editorial also appeared in the Spring 2016 issue of ARI's Autism Research Review International newsletter.

A common bacterium may play an important role in the genesis of autism, a new study suggests.

Marie-Julie Allard and colleagues note that Group B Streptococcus (GBS), a bacterium found in the lower genital tract of 15% to 30% of healthy pregnant women, is the leading cause of chorioamnionitis (an infection of the fetal membranes) and cerebral injuries in newborns. However, they say, little is known about the effect of maternal GBS exposure on children’s brain development. The researchers hypothesized that maternal infection and inflammation due to GBS may negatively impact the neurodevelopment of uninfected offspring.

Studying rats, Allard and colleagues found that GBS-exposed placentas exhibited chorioamnionitis, with more prominent abnormalities in male offspring. GBS-exposed male offspring also exhibited reduced thickness of periventricular white matter. “In addition,” the researchers say, “they exhibited autistic-like behaviors, such as abnormal social interaction and communication, impaired processing of sensory information, and hyperactivity.”

The researchers conclude, “Overall, these data show for the first time that gestational exposure to GBS plays an important role in the generation of neurodevelopmental abnormalities reminiscent of human autism spectrum disorders.”

“A sexually dichotomous, autistic-like phenotype is induced by Group B Streptococcus maternofetal immune activation,” M. J. Allard, J. D. Bergeron, M. Baharnoori, L. K. Srivastava, L. C. Fortier, C. Poyart, and G. Sébire, Autism Research, May 25, 2016 (epub prior to print publication). Address: Guillaume Sébire, Research Institute of the McGill University Health Centre, 1001-Decarie Boulevard, Glen Site, Block E, M0.3211, Montreal, QC H4A 3J1, Canada, [email protected]