Researchers have identified a unique blood marker that shows a link between gut bacteria and autism in some children diagnosed with the neurodevelopmental disorder.

In a new study published in the journal Translational Psychiatry, they found evidence of abnormal energy metabolism in a group of autistic children as a result compounds produced by gut bacteria frequently found in people with autism.

The discovery lays the groundwork for future blood tests to screen for autism and treat the condition early, says co-author Dr. Derrick MacFabe, director of the Kilee Patchell-Evans Research Group at the University of Western Ontario. He collaborated with researchers from the Arkansas Children’s Hospital Research Institute in Little Rock.

While gastrointestinal problems are common among children with autism, research to understand the connection and develop potential treatment is still in the early stages. To date, much of the effort has been directed at unravelling the genetic markers of the disorder, and toward early identification and behavioural intervention.

However, there is increasing evidence that autism, like many other disorders, is the result of a combination of genetic and environmental factors that affect the body and the brain, says MacFabe, whose research team focuses on the role of the gut and its trillions of important bacteria that are key to health.

The study provides more evidence that abnormal bacteria found in the gut of many children with autism produce a waste product that is carried in the bloodstream, affecting organ systems including the brain and, in turn, behaviour.

MacFabe says the new research is significant because it uncovers an important link between problems related to digestion, immune systems, metabolic problems and behaviour among some children with autism.

It also indicates there was no genetic factor causing the abnormal energy metabolism, and points to an environmental trigger.

“This paper shows we think environmental factors could play a much more major role than was previously thought,” he said.

The researchers tracked 213 children with autism and found 17 per cent of them had consistently abnormal levels of the unique blood markers and evidence of abnormal cell energy function.

That number is considered significant, said MacFabe, because the criteria were conservative and the tests were a snapshot that may not have captured all the cases of abnormal levels.

Autism rates have been climbing over the past decade, with an estimated one in 88 children diagnosed with the disorder, according to the U.S. Centers for Disease Control and Prevention.

“We’re looking at trying to find early ways of screening, and more importantly, not just to screen but to identify early,” said MacFabe.