Who has autism?
Estimates of the number of people in the UK with autism vary, however the National Autistic Society and the Department of Health state that about 700,000 people, just over 1.1 per cent of the population, are on the autistic spectrum. Between 20 and 33 per cent of adults with learning disabilities known to councils with adult social services responsibilities also have autism, totalling 35,000–58,000 people across England. This figure excludes the many people with autism who do not use social services, often because they are unable to obtain them. A King’s College London study  estimated that the cost of autism in adults is £25.5 billion per year. It is often stated that there is a difference in diagnosis rates between genders, and it is generally acknowledged that more males than females receive a diagnosis, though the ratios given for this vary from study to study. Concern has been expressed  that the new criteria for diagnosis in the ‘Diagnostic and statistical manual of mental disorders 5’ (DSM-5) makes it more likely that women and girls may not be diagnosed, as their autism is sometimes expressed in different ways to men and boys.
While the prevalence of autism appears to be increasing, this is largely attributable to a better understanding of the autistic spectrum and the nature of the condition among referrers and those – such as psychiatrists and clinical psychologists – who carry out diagnoses.