London - One in 100 adults has autism, according to a major report.
Experts say the disorder and similar conditions such as Asperger’s syndrome are far more widespread than previously thought.
And as with children, the study has found that autism is far commoner in males than females.
About 1 in 50 men has the condition in some form compared to just 1 in 300 women.
In addition, the report by the NHS Information Centre also found that a third of adults with learning difficulties was autistic.
Although autism has been widely studied in children, until recently little was known about the prevalence amongst adults.
Researchers asked more than 7,400 men and women a series of questions that can pick up signs of autism.
Those whose answers suggested they might have the condition were invited to take part in a more rigorous test.
In another survey researchers interviewed more than 300 adults with learning difficulties and their carers.
Their combined results found that 1.1 percent of all adults had some form of autism.
This is similar to the estimated prevalence amongst children - although some studies claim it could be as high as 1 in 60.
Mark Lever, chief executive of The National Autistic Society, said: '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 percent 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.'
Autism and Asperger’s cause a range of behavioural problems that vary between individuals.
Until about 20 years ago the conditions were considered relatively rare.
But in the 1990s there was a huge surge in the number of autism cases reported in children, after a wider diagnostic definition of the condition was introduced.
Autism also became far more high profile after a controversial study it may be triggered by the MMR vaccine – this link has since been widely disputed. - Daily Mail