Doctors close in on autism 'trigger'

By JEREMY LAURANCE

Doctors have taken a step towards identifying the cause of autism, the rapidly increasing brain disorder that leaves sufferers with difficulties in social interaction.

A study of brain tissue taken from affected patients has revealed that an immune system reaction leading to swelling of the brain could lie behind the condition.

If confirmed, doctors believe they could develop a test for autism and possibly a treatment to prevent the inflammation.

At present the condition cannot be diagnosed until the first signs of problems in communication appear, normally in the second year of life.

Professor Carlos Pardo-Villamizar, of Johns Hopkins University School of Medicine, who led the study, said: "These findings open new possibilities for understanding the dynamic changes that occur in the brain of autistic patients during childhood and adulthood."

But he said much more research was needed to establish the validity of the findings.

Autism affects about 535,000 people in Britain in varying degrees. It is four times more common in boys than girls. It runs in families and if one identical twin is affected the other is likely to be affected too, suggesting a strong genetic component.

But the condition has been increasing rapidly in the past decade, faster than would be expected for a genetic disorder, suggesting some environmental cause.

In Britain, the measles mumps and rubella (MMR) vaccine has been suggested as a cause, but extensive studies have failed to demonstrate a link. Birth complications, toxins, diet and viruses have also been proposed as potential causes but there is no strong evidence for any of these.

Recent research has pointed to immune system irregularities in children with autism but the results have been conflicting.

Professor Pardo and his colleagues tried to settle the question by narrowing their investigation to look at immune components inside the nervous system rather than at the immune system overall.

The researchers conducted autopsies of the brains of 11 people with autism aged from 5 to 44 who had died in accidents. Proteins called cytokines and chemokines were present in higher amounts in their brains than in those of normal controls, indicating inflammation.

They also found high levels of cytokines in the cerebrospinal fluid of six children with autism. The findings are published in the online edition of Annals of Neurology.

A test for autism could be done on cerebrospinal fluid extracted in a lumbar puncture.

- INDEPENDENT