Scientists have grappled with the puzzle of autism’s origins for decades; Now, a study suggests that a bad cold or flu during pregnancy could be the cause.
They have shown that when the mother’s immune system becomes stronger in response to a viral infection, it can impede the development of the growing baby’s brain.
Female embryos seemed protected from these effects, but a third of male embryos were affected to some degree, according to the research in mice.
This aligns with the fact that autism is more common in boys than girls, said the team at Cold Spring Harbor Laboratory (CSHL) in New York.
Researchers have discovered that autism can develop while the fetus is in the womb. When a pregnant woman gets a bad cold or flu, her immune response could cause a neurological reaction in the baby’s brain.
The researchers simulated a viral infection in mice and tracked the fetus’s reaction to how the mother’s immune system responded to a cold or flu virus, known as maternal immune activation (MIA).
MIA is activated when the immune system goes into overdrive, increasing levels of cytokines and chemokines that can cross the placenta and the baby’s blood-brain barrier.
Chemokines fight the flu by moving other immune cells, such as cytokines, to the site of infection.
Cytokines are small immune cells that fight harmful pathogens by summoning other immune cells creating symptoms such as fever, runny nose, and body aches.
Because the fetal brain is so sensitive to environmental cues in the womb, this reaction can cause a wide range of behavioral problems, including social impairments such as autism spectrum disorder.
Irene Sánchez Martín, postdoctoral student at CSHL, He said his recent experiments with mice showed that when the mother contracted a virus, the embryo’s brain development slowed down.
“The difference in my work is that I check what happened to the fetus 24 hours after exposure to maternal inflammation, instead of analyzing the behavior of the offspring as adults.”
Sánchez Martín focused on how prenatal inflammation caused by the cold or flu affected the brain of the developing fetus.
Prenatal inflammation has been linked to dysfunction in the growing fetus’s brain and can affect the way it organizes neural networks that connect cells and synapses.
If these are altered, the number of neurons and synapses in the brain can decrease, which has been linked to the development of autism in people.
One of the most important advances showed that, although female embryos appeared to be protected from MIA, about a third of male embryos showed signs of a brain development deficit consistent with autism.
Additional research is still needed to unravel the connection between the immune system’s reaction to a virus and how it affects the fetus.
Currently, more than 5.4 million people in the US are diagnosed with autism and between 40 and 80 percent are likely related to genetics, but that still means that between 20 and 60 percent are caused by other factors.
Early diagnosis is crucial in autism because there are currently no treatments and it takes years to test and diagnose the disorder.
Sánchez Martín said his research is still in the early stages and more needs to be done to definitively link cold and flu viruses to autism.
However, he is hopeful that future findings can help doctors recognize the early warning signs of autism before the child is born.