"Autism cases 'levelling off'"
Find a Conversation
|Fri, 08-08-2003 - 1:24am|
Tuesday, 22 July, 2003, 10:45 GMT 11:45 UK
Autism cases 'levelling off'
"The controversial MMR vaccine has not triggered an increase in the number of children being diagnosed with autism, according to experts.
Researchers at University College London say figures actually show that the number of new cases has levelled off and may have peaked 11 years ago.
They also said that the rise in new cases throughout the 1980s and early 1990s may have been simply due to greater awareness of the condition.
Nevertheless, the study found that parents were now more likely to blame their children's autism on the MMR vaccine.
Professor Brent Taylor and colleagues at UCL identified 567 children born between 1979 and 1998 who were diagnosed with autism in north-east London.
They found that the number of children being diagnosed with autism peaked in 1992.
" The appearance of autism appears to have stabilised "
University College London researchers
They reported that the number of new cases levelled off between 1992 and 1996, with between 45 and 50 children being diagnosed with the condition.
This was equivalent to 2.6 cases for every 1,000 live births.
The researchers said that if autism was caused by the MMR vaccine then figures would have jumped sharply throughout the early 1990s. The MMR vaccine was introduced in Britain in 1988.
But writing in the journal Archives of Disease of Childhood, the researchers said: "The appearance of autism appears to have stabilised."
They researchers also dismissed claims that the vaccine can cause developmental or bowel problems in children.
"The claims that MMR vaccine is involved in the initiation of autism, and/or with regression, and/or with bowel problems associated with autism are not supported by any credible scientific evidence, while there is compelling and increasing evidence showing no association."
The researchers said controversial research published in 1997, which suggested a link between the MMR vaccine and autism, appeared to have influenced parents.
Before the study was published, just two out of 46 parents had suggested the vaccine had caused autism in their child.
However, afterwards it was cited in six out of 30 cases.
"Before August 1997, parents incriminated trigger factors such as domestic stress, seizures or viral illness.
"Post 1997, parents were more likely to attribute regression to vaccination, especially the MMR vaccine," the researchers said.
The UK's National Autistic Society welcomed the study.
Stuart Notholt, its director of policy, said it was difficult to get accurate figures on the incidence of autism.
"Data on the numbers affected by autistic spectrum disorders continue to be sparse and it has been difficult to compare current numbers with figures from earlier years," he said.
However, he said the number of new cases could be expected to level out if doctors were becoming more aware of the condition and if there was no external cause, such as a vaccine.
"It might be expected that with growing familiarity with autistic spectrum disorders, over a period of time, provided there were no external factors influencing onset, prevalence figures would begin to level out."
Link to research article in Arch Dis Child 2003; 88:666-670 (.pdf):