In recent years, there has been plenty of speculation surrounding the various potential causes of autism. And while most experts believe there are likely multiple factors that contribute to autism cases in different situations, we have yet to really nail any of them down. But now a team of scientists has pinpointed what appears to be the cause of about 25 percent of autism cases worldwide.
In adults, the blood-brain barrier is strong enough to prevent any antibodies from making their way to the brain tissue, but this isn’t always the case with unborn babies, whose brains and blood-brain barriers are still developing and may be porous. When specific maternal antibodies cross the blood-brain barrier and react with fetal brain tissue, a type of autism known as maternal antibody-related autism spectrum disorder (MAR ASD) can result.
The researchers have discovered that a specific type of antibody that some mothers produce can pass through their unborn children’s blood-brain barriers and react negatively with their developing brain tissue. Now if we could just discover why certain people produce these antibodies, we could give new mothers a better understanding of their children’s autism risks, diagnose autism earlier, and potentially work on preventing it.
Luckily, a laboratory mouse model, developed by identifying the particular parts of a protein where antibodies bind, is now helping researchers better understand the phenomenon. The mice mimic much of the behavior found in people who have developed autism because of maternal antibodies crossing the blood-brain barrier.
“We’ve really needed an animal model that mimics what we see clinically,” says senior author Judy Van de Water, professor in the UC Davis MIND Institute and Center for Children’s Environmental Health. “We can then understand the mechanisms, the pathology, and what the brains of these animals look like. In time, we might be able to use it to develop therapeutics.”
The mouse models exhibit enlarged heads, repetitive grooming behaviors, and issues with social interaction. These patterns are similar to autism symptoms in humans with MAR ASD. Although they don’t exactly replicate autism, the mouse models are the closest thing we’ve ever had to an exact representation of MAR ASD.
“Autism is a purely human disorder, you’re never going to have an autistic mouse,” says postdoctoral researcher and one of the study’s authors, Karen L. Jones. “We were pleasantly surprised at how well the model maps to the human condition.”
What the researchers discovered is that the maternal antibodies and the adverse reaction they cause in fetal brain tissue are indeed capable of causing autism rather than simply being a byproduct or proxy of another biological process. Mothers of children with autism are 21 times more likely to possess these antibodies than mothers of neurotypical children.
In the near future, researchers will study how antibodies are capable of disrupting brain development. Hopefully, someday they’ll be able to use this information to develop new treatments as well.Whizzco