Adults with a more severe learning disability also have a greater likelihood of having autism according to today's report; Estimating the Prevalence of Autism Spectrum Conditions in Adults: Extending the 2007 Adult Psychiatric Morbidity Survey.

The report combines data from the Adult Psychiatric Morbidity Survey (APMS) 2007 with findings from a new study based on a sample of people with learning disabilities living in private households and communal care establishments. It aims to; estimate the prevalence of autism in England, furthering previous research that suggests people with learning disabilities are more likely to have autism; and address the fact that the APMS did not include people with severe learning disabilities.

Today's report estimates that the prevalence of autism:

• Is 1 per cent in the general population.
• Is approximately 35 per cent among adults with severe learning disabilities living in private households.
• Is approximately 31 per cent among adults with mild or severe learning disabilities living in communal care establishments.
• Increases with greater severity of learning disability or lower verbal IQ.

In terms of the new study that forms part of today's report; a sample of adults from disability registers in Leicestershire, Lambeth and Sheffield, were invited to take part between August 2010 and April 2011. People were excluded from the new study if they were sufficiently able to have taken part in the APMS 2007.

The overall response rate for the new survey was 20 per cent in private households (83 interviews). Sixty four per cent of communal care establishments approached took part in the study. Among these, the response rate for individual participants was 69 per cent (207 interviews).

NHS Information Centre chief executive Tim Straughan said: “While is it is important to note that these estimates are based on a study of only three areas of the country, they offer a new insight into the prevalence of autism among people with learning disabilities.

“This information will be of particular importance for those who plan and provide services to support those with learning disabilities or with autism.”

Read the full report 'Estimating the Prevalence of Autism Spectrum Conditions in Adults'

Notes to editors.

1. The NHS Information Centre is England's authoritative, independent source of health and social care information. It works with a range of health and social care providers nationwide to provide the facts and figures that help the NHS and social services run effectively. Its role is to collect data, analyse it and convert it into useful information which helps providers improve their services and supports academics, researchers, regulators and policymakers in their work. The NHS Information Centre also produces a wide range of statistical publications each year across a number of areas including: primary care, health and lifestyles, screening, hospital care, population and geography, social care and workforce and pay statistics.
2. The new study presents the prevalence of autism among adults aged 18 years and over. It was carried out for the NHS Information Centre for Health and Social care by the University of Leicester, the Leicestershire Partnership NHS Trust, the National Centre for Social Research, and the University of Glasgow. The study was led by Professor Terry Brugha of the University of Leicester, who also led on autism research for the Adult Psychiatric Morbidity Survey (APMS) 2007 (http://www.ic.nhs.uk/pubs/asdpsychiatricmorbidity07). The findings of this study are estimates from a sample survey and so each figure has a margin of error. There is additionally some error introduced as a result of survey non-response; in particular, it should be noted that response rates in Leicestershire were much higher than in Lambeth and Sheffield.
3. Autism, including childhood autism and Asperger syndrome, is a neuro-developmental disorder. Childhood autism and Asperger syndrome were first described in the 1940s , , and now fall within the concept of a broader spectrum of autism , . In March 2010, the Government published a new national strategy for autism and guidance for the condition , with the view to improving the quality of services provided to adults with autism in England. Such improvements can only be achieved if the number of people with recognised and unrecognised autism in the general population is quantified.
4. People with learning disabilities (defined by a significant intellectual impairment with onset before adulthood and deficits in skills needed for daily functioning) could not take part in the APMS 2007 because the consent forms, questionnaires and assessments were designed for people with full decision-making capacity.
5. For media enquiries please call 0845 257 6990 or email mediaenquiries@ic.nhs.uk