Previous research has found that lots of children with psychological problems remain undiagnosed by health services. However, there has been little research into how many children with autism spectrum disorders (ASDs) fail to receive a diagnosis. A team of researchers led by Ginny Russell from the University of Exeter looked at information from a long-term study of 14,536 children in the Bristol area. By using information from the study they were able to see which of the children showed symptoms of autism. They found that 55% of children with autistic traits at the same levels as those who had an autism diagnosis had not been identified as needing extra support from education or specialist health services. Of those who were identified as having special needs only 37.5% had been formally diagnosed with an ASD. For children with impairment at the same level as that associated with an Asperger's syndrome 57% had no special provision at school and were not accessing specialised health services. 26% of the children in this group had an ASD diagnosis.
Russell, Ginny ... [et al] - Identification of children with the same level of impairment as children on the autistic spectrum, and analysis of their service use Journal of Child Psychology and Psychiatry June 2010, 51(6), 643-651