If they are clusters then that could point to localised environmental triggers. Without urgent research, appropriate action cannot be taken. A recent survey of Health Authorities undertaken by David Thrower, a parent, has thrown up stark disparities in estimated prevalence rates between health authorities. This only illustrates the fact that health and local authorities cannot plan service provision on the basis of accurate data. Indeed, no Government agency has an accurate idea of the service needs of people with autism and Asperger syndrome.
Professionals currently differ widely in the way they apply the criteria.
Diagnoses may be recorded, unhelpfully, in different ways in case notes and centralised data collections. Uniformity of diagnostic classification will be key to useful data collection. Reports of an increase in prevalence have been attributed to improvements in diagnosis, as well as greater public awareness of autism and Asperger syndrome. Howlin and Moore found that the average age of diagnosis of autism was 6 years old , and that this represented a delay of just under 4 years from when families first sought professional help to the diagnosis. The average age of diagnosis of Asperger syndrome was 11 years old .