October 3, 2011

New Animal Model for Autism

By Alicia Rose DelGallo, Ivanhoe Health Correspondent

(Ivanhoe Newswire) -- Mice with a single defective gene are showing striking parallels to humans with autism. According to a study published in the September 30th issue of Cell, a Cell Press publication, the mouse model offers several promising discoveries.

The study involved developing mice lacking CNTNAP2, a rare variant of the gene that has been shown to cause a form of autism known as cortical dysplasia-focal epilepsy syndrome (CDFE).

Researchers found that the animals displayed very similar behaviors of human autism. Not only were they hyperactive, they suffered epileptic seizures, repetitive behaviors, and abnormal social interaction.

The study also revealed a closer look at the animals' brains, which showed problems in the development of the neural circuitry, including abnormal migration of neurons, abnormal activity of the neural network, and fewer interneurons that connect neurons carrying impulses to the central nervous system with those sending them to the rest of the body.

These observations are consistent with emerging theories that autism is characterized in the brain with "long-range disconnectivity and short-range increases in connectivity," according to Geschwind.

So, why is this new animal model for autism important? In addition to providing verification of the gene's association with autism, the study also provides insight into the biological mechanism that underlies the disease, as well as new ways to test and develop treatments.

"To develop new drugs, it is critical to have good animal models," said author Daniel Geschwind of the University of California, Los Angeles.

Mice carrying the defective gene responded well to treatment with risperidone, an antipsychotic drug, and the first approved by the FDA for treating symptoms of autism.

According to the author, animals given the drug were less hyperactive, showed less repetitive grooming behavior and were better at building nests. However, they did not show any improvement in social interactions. All of these reactions are consistent with those of human patients taking the drug.

"I did not necessarily expect to see the same behaviors in mice as in humans because we don't know how conserved the pathways are. This suggests they are very conserved- surprisingly so," Geschwind was quoted as saying.

He adds that the findings are a big step towards developing new drugs and strategies for treating autism.

SOURCE: Cell, published online Thursday September 29, 2011; phone interview with Dr. Daniel Geschwind conducted on Wednesday September 28 at 11:15 am EST.