Amidst the myriad of effects we’ve found our gut microbiome can have on our daily lives, a recent study finds that it may also affect behaviors in our offspring, even long after they’ve exited the womb.
Two newer studies using rats published by MIT and the University of Massachusetts Medical School explored the idea that the microbial population of the mother’s gut can result in higher rates of offspring demonstrating atypical social behaviors in rats, such as ignoring new cage mates or engaging in repetitive behaviors. Viral infections have been associated with increased rates of several neuro-developmental disorders, such as autism and schizophrenia, for many years. These recent studies also find that the bacterial population in mother rats correlates with offspring displaying behaviors similar to humans with autism spectrum disorders, as well as atypical brain development.
Having offspring on the autistic spectrum is not necessarily something to be feared. The list of people on the autism spectrum who have contributed to human knowledge in a significant way is too long to list here. However, an analysis of the life and habits of Sir Isaac Newton and Albert Einstein performed at Cambridge University suggests they both exhibited many behaviors associated with autism. More recently the Autism Research Centre at Cambridge also found that those in STEM-related jobs scored an average of 3 points higher on the Autism Spectrum Quotient, a 50 question test for determining where an individual likely falls on the autistic spectrum, with a higher score testing as exhibiting more autistic behaviors and a lower score exhibiting fewer.
The current theory behind why the viral infections may result in more behaviors associated with autism is that when the mother’s immune system is triggered, it produces TH17 cells. These cells are stimulated to release molecules that appear to be the cause of the atypical brain development in the fetus. The area of the brain that displays the atypical development is the somato-sensory cortex, which, according to Gloria Choi of MIT, “tells an animal where its body parts are and how their positions change as a result of movement.” This area of the brain experiences increased neuronal activity, which when decreased also causes a decrease in the observed atypical behaviors.
This change in brain development also correlates in pregnant women with a lower concentration of Bifidobacterium spp. in the gut; although it is unclear if a similar mechanism to the viral infections is occurring. However, the California Institute of Technology found that mice infected with a “virus-like” molecule during pregnancy to initiate the reaction described above had offspring with a different gut microflora than those who did not. Mice born from mothers treated with the virus-like molecule and later treated with Bacteroides fragilis introduced into their microbiome after birth displayed more typical behaviors similar to the mice from untreated mothers.
Of course, the idea of “normal” behavior is completely relative, and the link between atypical behavior in mice and autism in humans is a rather large leap. However, these studies demonstrate that the maternal microbiome can affect fetal brain development, which can then be further affected by changes in the newborn’s microbiome. These studies strengthen what we already suspect; the link between who we are and what is in our gut is very powerful.
By Kate Massey
Technical Support Specialist II