Swelling of brain may be linked to autism, study finds

Doctors have taken a step towards identifying the cause of autism, the rapidly increasing brain disorder. A study of brain tissue from affected patients show has revealed that an immune system reaction leading to swelling of the brain could lie behind the condition.

Doctors have taken a step towards identifying the cause of autism, the rapidly increasing brain disorder. A study of brain tissue from affected patients show has revealed that an immune system reaction leading to swelling of the brain could lie behind the condition.

If confirmed, doctors believe that 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 possibilities for understanding the dynamic changes in the brain. Although they may lend themselves to the development of new medical treatments for autism, much more research is needed."

Autism affects an estimated 535,000 people in the UK in varying degrees. It is four times more common in boys than girls and runs in families. If one identical twin is affected the other is likely to fall victim too, suggesting a genetic component.

But the condition has been increasing in the past decade at a faster rate than expected for a genetic disorder, suggesting an environmental cause. In Britain, the measles mumps and rubella (MMR) vaccine was suggested as a cause, but extensive studies have failed to demonstrate a link. Birth complications, toxins, diet and viruses have also been blamed.

Research has pointed to immune system irregularities in children with autism but the results have been conflicting. Professor Pardo and his colleagues narrowed their investigation to look at immune components inside the nervous system rather than at the immune system overall. The researchers conducted post-mortem examinations of the brains of 11 people with autism aged from five to 44, who had died in accidents.

Proteins called cytokines and chemokines were present in higher amounts 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 in the online edition of Annals of Neurology.

Professor Pardo said: "This ongoing inflammatory process was present in different areas of the brain ... The pattern of cellular and protein findings indicate they are part of the innate immune system in the brain and do not appear to be caused by immune abnormalities from outside the brain."

A spokesperson for the UK National Autistic Society said: "Several scientists have worked on the possible link between the immune system and autism. This paper carries this interest further."