A new report has found that adults with a more severe learning disability have a greater likelihood of having autism.

The report, ‘Estimating the Prevalence of Autism Spectrum Conditions in Adults: Extending the 2007 Adult Psychiatric Morbidity Survey’, also found that this group, mostly living in private households, was previously ‘invisible’ in estimates of autism.

The report, by the University of Leicester and published by the NHS Information Centre, presents findings from a study based on a sample of people with learning disabilities living in private households and communal care establishments in Leicestershire, Lambeth and Sheffield between August 2010 and April 2011. Its findings are combined with information from the Adult Psychiatric Morbidity Survey (APMS) 2007.

Dr Terry Brugha, Professor of psychiatry at the University of Leicester and also a consultant psychiatrist working in the NHS with the Leicestershire Partnership NHS Trust, led the research. He said: “We were surprised by how many adults with moderate to profound learning disability had autism because previous estimates pointed to lower rates in this group. Because they form a very small part of the adult population, when we added these new findings to the rate we had previously found in adults living in private households, and able to take part in our national survey in 2007, the overall percentage of adults in England with autism did not increase significantly over our 2007 estimate of 1%.

“Our finding that about 60% of men with profound learning disabilities and 43% of women with profound learning disabilities have autism has never been shown previously. "It may also seem surprising how many live at home with parents or carers who provide 24 hour care and shoulder a considerable burden: 42% of men and 29% of women with severe learning disabilities living with family members and in other private households have autism. Taken together with the 2007 survey findings this means that most adults with autism live in private households, and before these two surveys they remained largely invisible. “This new information will be of particular importance for those who plan and provide services to support those with learning disabilities. In March 2010, the Government published a 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 is quantified. The strategy gave special emphasis to the need to train staff who have responsibility for identifying people with autism and their care. It will be vital to repeat such studies in future years in order to make sure that the national strategy is working effectively.”

Sally-Ann Cooper, professor of learning disabilities at the University of Glasgow, who also contributed to the study, added: “Until now routine statistics have not been gathered on the numbers of people with learning disabilities who also have autism leaving this as a hidden problem. Our study clearly shows that the more severe to profound an adult’s learning disability is, the more likely they will be found to have autism if actually assessed.”

Mark Lever, chief executive of The National Autistic Society welcomed the report’s findings. “Contrary to media hype this study shows that autism has been with us for a long time and that a large group of adults have been consistently overlooked by services and society. There has long been a tendency to view autism as solely a condition affecting children but this is the first study to find that the prevalence of autism is roughly the same for adults as it is for children. “Many people with autism currently face a battle to get appropriate support, with 63% of adults saying they do not have enough to meet their needs. Now that we know how many adults with autism there are in England local authorities should be better able to estimate local need and plan services accordingly.”