Aims: To determine the prevalence of autism in a UK sample.
Background: We developed the CAST, formerly known as the Childhood Asperger Screening Test but renamed as the Childhood Autism Spectrum Test. The change of name reflects that it was originally designed for a prevalence study of Asperger Syndrome in childhood but is useful for screening all children who may be autistic. The CAST discriminates autistic children from typical children well, and CAST scores show strong heritability in a twin study, suggesting it is a reflection of the underlying genetic liability for the number of autistic traits a person has.
Method: We used the CAST as a screening instrument in a large population study of 20,000 primary school age children in Cambridgeshire.
Results: We confirmed recent studies from other prevalence studies that autism affects approximately 1% of the population. This study also found for the first time that for every 3 known cases of autism, there are 2 undiagnosed cases. This means that there are autistic individuals who remain undetected through the school years who may benefit from support and intervention.
Importance: This showed that autism is far more common than was previously thought. This also showed that the CAST can be used as a screening instrument in epidemiology research and has been translated into many languages, for comparative prevalence studies. This project is being replicated in China in 3 provinces, using translations of the CAST.
Relevance: Knowing the prevalence of autism can help commissioners plan services for the number of children who will need support.
Funding: The Shirley Foundation, and the Big Lottery Fund.
- Factor Structure of the Bulgarian CAST: (Childhood Autism Spectrum Test), Journal of Intellectual Disability - Diagnosis and Treatment 4:117-128 (2016), M Vulchanova, L Djalev, M Stankova, V Vulchanov, C Allison, S Baron-Cohen
- Exploring the Underdiagnosis and Prevalence of Autism Spectrum Conditions in Beijing, Autism Research 8:250-260 (2015), X Sun, C Allison, F Matthews, Z Zhang, B Auyeung, S Baron-Cohen, C Brayne
- The Childhood Autism Spectrum Test (CAST): Sex Differences, Journal of Autism and Developmental Disorders 38:1731-1739 (2008), J. G. Williams, C. Allison, F. J. Scott and P. F. Bolton
- The Childhood Asperger Syndrome Test (CAST): Test-retest reliability in a high scoring sample, Autism 11(2):173-185 (2007), C. Allison, J. Williams, F. Scott, C. Stott, P. Bolton, S. Baron-Cohen and C. Brayne
- The CAST (Childhood Asperger Syndrome Test): Preliminary development of UK screen for mainstream primary-school children, Autism 6(1):9-31 (2002), F. Scott, S. Baron-Cohen, P. Bolton and C. Brayne