Viral Infection in Mothers May Increase Autism Risk in Children

Scientists continue to delve into autism research, trying to discover what factors make a child more susceptible to the disease. Now, they've found out a bit more about the condition. It turns out that activating a mother's immune system during her pregnancy disrupts the development of neural cells in the brain of her offspring and damages the cells' ability to transmit signals and communicate with one another.

In order to learn a bit more about how viruses might impact pregnancy, the researchers examined mice and rats. They compared the brains of the offspring of rodents whose immune systems had been activated and those of animals whose immune systems had not been activated. It turns out that the pups of animals that were exposed to viral infection had much higher brain levels of immune molecules known as the major histocompatibility complex I (MHCI) molecules.

"This is the first evidence that neurons in the developing brain of newborn offspring are altered by maternal immune activation," said Kimberley McAllister, one of the researchers, in a news release. "Until now, very little has been known about how maternal immune activation leads to autism spectrum disorder and schizophrenia-like pathophysiology and behaviors in the offspring."

In fact, the researchers found that high MHCI levels impaired the ability of the neurons in the newborn mice's brains to form synapses, which are the tiny gaps separating brain cells that transmit signals. Earlier research has suggested that ASD and schizophrenia may be caused by changes in the development of connections in the brain, especially the cerebral cortex.

That's not all the researchers did, though. They also experimentally reduced MHCI to normal levels in neurons from offspring following maternal immune activation. This caused synapse density to return to normal levels in those neurons.

"These results indicate that maternal immune activation does indeed alter connectivity during prenatal development, causing a profound deficit in the ability of cortical neurons to form synapses that is caused by changes in levels of MHCI on the neurons," said McAllister in a news release.

The findings are important for better understanding how immune activation may affect pregnancy. The research could be crucial for development future treatments and therapies to improve the lives of individuals with these neurodevelopmental disorders.

The findings are published in the Journal of Neuroscience.