A drug being developed for depression has been shown to reduce two of the three signature symptoms of autism in mice, according to a new study.

The experimental drug, GRN-529, increased social interactions and reduced repetitive self-grooming behavior in a naturally occurring inbred strain of mice that normally display autism-relevant behaviors, like abnormal social interactions, impaired communication and repetitive behaviors.

Researchers from the National Institutes of Mental Health (NIMH) and Pfizer Worldwide Research and Development found that when “autistic mice” were injected with GRN-529, which targets glutamate, a neurotransmitter chemical in brain involved with activating neurons and tied to symptoms of autism, the mice almost immediately showed fewer repetitive grooming and more normal social interactions, but their communication was still impaired.

Researchers noted that GRN-529 injections also completely stopped repetitive jumping in another strain of mice.

While experimental findings in mice are not always synonymous to humans, researchers said that because GRN-529 is already being tested an overlapping condition, depression, the findings may be more readily applied to humans.

There are currently no drugs on the market to treat symptoms of autism, and until recently, experts had thought that the brains of autistic patients were predisposed before diagnosis until researchers found that the developmental disorder may be caused by faulty genes that have a real-time effect on patients’ brains.

"Many cases of autism are caused by mutations in genes that control an ongoing process – the formation and maturation of synapses, the connections between neurons. If defects in these connections are not hard-wired, the core symptoms of autism may be treatable with medications," Jacqueline Crawley, of the NIH's National Institute of Mental Health said in a statement released on Wednesday.

“Our findings suggest a strategy for developing a single treatment that could target multiple diagnostic symptoms,” Crawley added.

Experts say that the latest research, published in the April 25 issue of the journal Science Translational Medicine, paves the way for developments of future treatments that target autism’s core symptoms.

"While autism has been often considered only as a disability in need of rehabilitation, we can now address autism as a disorder responding to biomedical treatments," NIMH director Dr. Thomas Insel said in a statement.

One in 88 U.S. children have autism spectrum disorders, according to the latest report by the U.S. Centers for Disease Control released last Thursday, an overall increase of 25 percent since the government’s last analysis in 2006.

The CDC estimates that about one in 45 boys and one in 252 girls are on the autism spectrum disorder, and it is likely that the developmental condition affects roughly 1 million U.S. children and teens.

Autism, a developmental disorder that affects the brain’s proper development of social and communication skills, differs greatly in severity and symptoms, and often goes unrecognized, particularly in mildly affected children, and parents don’t generally notice symptoms until the child is 18 months old and clinicians aren’t able to diagnose autism until children start exhibiting the first behavioral and language symptoms of autism at about two years of age.

Mouse pays a social visit to a strange animal. The experimental agent increased such sociability, which is impaired in autism.
Credit: NIMH Laboratory of Behavioral Neuroscience

There is no cure for autism, but experts say that treatment is best delivered as early as possible to prevent or reduce the onset of disabling symptoms associated with the disorder.