Could blood and urine test be used to diagnose autism?

The results revealed that children with autism had greater protein damage when examining plasma in their blood, which causes higher levels of an oxidation marker called dityrosine as well as sugar-modified compounds known as advanced glycation end-products.

"We have found that the power of measuring damaged proteins to the brain may be a cause for a development of autism," Dr. Paul Thornalley, professor of systems biology at the University of Warwick and one of the study's lead researchers, explained to CNN.

According to Thornalley, previous research has also shown a connection between autism and proteins that were not damaged, the reverse of this study.

"Our discovery could lead to earlier diagnosis and intervention. We hope the tests will also reveal new causative factors," Dr. Naila Rabbani, another lead researcher from the University of Warwick, told The Guardian.

"With further testing we may reveal specific plasma and urinary profiles – or 'fingerprints' – of compounds with damaging modifications. This may help us improve the diagnosis of ASD and point the way to new causes of ASD,” she said.

While the new results appear promising, some researchers have expressed caution about the study’s small sample size and the study’s lack of a concrete diagnosis plan.

"This study may give us clues about why autistic people are different but it does not provide a new method for diagnosis. It is far too early for that," Dr. James Cusack, director of science at the UK autism research charity Autistica, told the BBC.

"We don't know whether this technique can tell the difference between autism, ADHD, anxiety or other similar conditions. The study also only looked at a small group of people," he pointed out. "The best way to diagnose autism is still through clinical interview and observation."

But despite the criticism, the scientists behind the research are calling it a "first step" toward developing a simple test. They aim to move forward with further research, performing the tests on a larger group including younger children.

"We have the method, we have everything. All we need to do is repeat it," Rabbani said. "I would really like to go forward with younger children, maybe two years, or even one year old. Then the next step will be to validate in a larger cohort. Then the tests will be ready for screening."

More than 3.5 million people in the U.S. currently live with autism spectrum disorders, according to statistics from the Autism Society. The development disorder, which mainly affects social interaction and leads to behavioral problems, is estimated to have genetic causes in 30 percent of cases. The other 70 percent of autism cases are believed to be caused by mutations of genetics and environmental factors combined.

Although many individuals with autism go on to live normal productive lives, 35 percent of young adults with the disorder are unable to work jobs or pursue higher education after high school.

Doctors currently rely on a series of behavioral tests to diagnose the disorder. These can take a great deal of time and are not always accurate. If a blood or urine test could provide a faster and more definitive diagnosis, it would go a long way to ensure young children received the treatment and resources they need earlier on.

However, although experts see the new research as promising, they are still cautioning that such a test is still a long way from being viable.

"This is a promising area; however, this is a very long way indeed from a 'test for autism,' " Dr. Max Davie, spokesman for the Royal College of Paediatrics and Child Health, said. "It is important that it is not adopted with too much enthusiasm."