Last Updated: 2003-07-22 8:38:58 -0400 (Reuters Health)

LONDON (Reuters) - Cases of autism in Britain have leveled off after hitting a peak in the early 1990s, which itself may have been caused by greater awareness of the illness and better recording systems, scientists said Tuesday.

Professor Brent Taylor, of the Royal Free and University College Medical School in London, said the number of children with the illness has steadied after a continual rise.

"We have shown a leveling-off since the early 1990s in the previously rising recorded prevalence of autism," Taylor said in a report in the Archives of Disease in Childhood.

He added there is no scientific proof that the triple measles, mumps and rubella (MMR) vaccination causes the illness.

"The claims that MMR vaccine is involved in the initiation of autism...are not associated with any credible scientific evidence, while there is compelling and interesting evidence showing no association," he said.

New cases of autism rose between 1979-1992 but the most recent figures show the illness has leveled off to about 45-50 cases a year.

The age at which children are diagnosed with autism has also declined since 1985.

Autism usually occurs before the age of 30 months when children who have developed normally start to deteriorate. They become withdrawn and self-absorbed and are often unable to communicate. The cause of autism is unknown and it is more prevalent among boys than girls.

A minority of autistic children, who are known as autistic savants, show remarkable artistic, musical or mathematical skills.