A BLOOD test that can detect autism in infancy has become a possibility after new research in the United States.

Scientists have discovered a set of biological markers in the blood of autistic children that differ significantly from those seen in normal development, suggesting a potential means of diagnosing the disorder long before it would usually become apparent.

Such a test would be an important breakthrough because it would allow doctors to start therapy designed to minimise the impact of autism and to help sufferers to enjoy a more fulfilling life. While there is no cure for the disorder, there is evidence that interventions such as behavioural therapy and specialised teaching may improve language, communication and social interaction skills.

The effects of these approaches, however, are generally greater the earlier they start, making prompt diagnosis of autistic spectrum disorders critical. These are not usually detected until children are aged between 2 and 3 at the earliest, when difficulties with communication and other social skills start to become more apparent. The findings, from a team at the University of California, Davis, also promise new insights into the causes of autism that could eventually lead to improved treatments.

David Amaral, who led the research, said: “A simple blood test would have enormous implications for diagnosing, treating and understanding more about the underlying causes of autism. Not being able to detect autism until a child is close to three years old eliminates a valuable window of treatment opportunity when the brain is undergoing tremendous development.”

In the study, details of which were presented yesterday at the International Meeting for Autism Research in Boston, Massachusetts, Dr Amaral’s team took blood samples from 70 children between the ages of 4 and 6 diagnosed with autism, and from 35 children without the condition. They found that children with autism have elevated concentrations of two kinds of immune cells — antibody-producing B cells are increased by 20 per cent, and natural killer cells are increased by 40 per cent.

“Scientists have long suspected there were distinct biological components to autism but the technology needed to reveal them has only recently become available,” Dr Amaral said. “There is a growing view among experts that not all children with autism are doomed to autism at birth. Studying the biological signs of autism could lead to new ways to prevent the disorder from ever occurring. Even if it can’t be prevented, intervening early in life could greatly improve the outlook for children with autism.”

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