But after comparing a study by the Maudsley of autistic children born before 1980 with one of autistic children in Stafford born before 1992 and 1995, he found there had been no change in the numbers with this particular type of autism. His comments follow research, published on the British Medical Journal's website earlier this month, which showed the number of autism cases had continued to rise while MMR coverage remained the same. Maybe there is an environmental factor - but we don't know what it is. The NAS estimates there are 91 cases of autism spectrum disorders per 10,000 people. The NAS spokesman added that it was difficult to accurately plot how many cases of autism there were because there was no central register, and no way of measuring year on year trends.
Anecdotal reports suggest that there is a significant increase in numbers of cases of autism.
Until figures are collected systematically we will continue to have to guess at the true number of cases and whether it represents a real increase.