Paul Shattock from the Autism Research Unit, Sunderland: "We're optimistic."

Victoria Beck, from New Hampshire, claims to have stumbled across the treatment when her five-year-old boy was given a drug for a stomach complaint.

The drug - a hormone called secretin - stimulates the pancreas to produce the enzymes necessary to break down food, and is used in the diagnosis of gastro-intestinal illnesses.

But Mrs Beck says that her son Parker's autism problems also showed "remarkable signs of recovery" within weeks of taking secretin. She says he was a totally non-responsive child who was soon able to concentrate on specific tasks. She says he was able to sleep at nights and became potty trained.

Encouraging

The experience of Mrs Beck and her son has been tested in a limited trial on over a hundred other autistic children and has shown encouraging results.

Paul Shattock from the Autism Research Unit at the University of Sunderland in the UK says secretin should now be the subject of a much larger study.

He believes the drug's success makes perfect sense: "There is a school of thought, to which we subscribe, that autism is the consequence of a metabolic disorder, in that the intestines are not breaking the foods down properly."

Paul Shattock says food products that are not broken down properly can pass into the blood stream and into the brain with a "morphine-like effect".

"It is suspected that secretin stimulates the pancreas which will break these things down further. The idea is not totally new. It's been around for a while, but it's one of those things that you would have to be fairly daring to try it, and it seems to have been tried with Mr Beck's son and great things seem to have resulted."

Experimental

The US Autism Research Institute says it is aware of about 120 autistic children that have been treated with secretin so far.

It says there are fewer than 20 doctors using the drug but none of them wish to be identified, because the treatment has not been specifically approved by the Food and Drug Administration, and because they fear a flood of new patients.

Paul Shattock says he knows of just a handful of physicians who have experimented with the drug and says they are "enthusiastic" with the effects. But he warns that secretin has not worked for all the children it has been tried on.

"It's not a miracle cure, but it makes sense and we are hopeful."

There are over half a million people in the UK who are affected by autism-related disorders.