The term autism spectrum disorders (ASD) covers a range of conditions including autism, atypical autism and Asperger’s syndrome. ASD may occur with any level of intellectual ability, and the associated disability ranges from subtle to severe. It has been suggested that ASD affects at least 60 per 10 000 children under 8 years of age.1 A systematic review of prevalence studies2 suggested a figure of 20 per 10 000 for ASD and around 7 per 10 000 for typical autism. A more recent study in the Thames region3 estimated a prevalence of 116 per 10 000 in 9–10-year-old children. A recent review4 covering research on these conditions debates whether the increased prevalence represents better recognition or a true increase.

In July 2007 the Scottish Intercollegiate Guideline Network (SIGN) published a clinical guideline5 covering the assessment, diagnosis and clinical interventions for these conditions. The full guideline contains much detail not incorporated in this review, and the reader is encouraged to refer to the full guideline. It is accompanied by two booklets, one for young people and the other for parents and carers, and stresses the importance of providing information and support. There is a checklist for provision of services and information, recommendations for audit and research, a quick reference guide, and a detailed comparison of the ICD-10 and DSM-IV definitions of autism.

Within the guideline the recommendations are graded. In this review the grades are indicated only for those recommendations with an A or B grade. Grade A is based on at least one high quality meta-analysis, systematic review of RCTs, or RCT with a very low risk of bias and directly applicable to the target population; or on a body of evidence consisting principally of well conducted meta-analyses, systematic reviews, or RCTs with a low risk of bias, directly …