Autism diagnosis surge points to better detection, not sudden biological rise

Sharp increases in recorded autism diagnoses in the US and UK are being driven largely by improved recognition, changing criteria and greater access to assessment, researchers say.

Rates of autism diagnoses have climbed sharply in recent years, but researchers say the trend is better understood as a story of changing detection than of a sudden biological surge. In the United States, a study published on PubMed found diagnosis rates among children and adults rose by 175% between 2011 and 2022, with the steepest relative increase among 26-to-34-year-olds. British data tell a similar story: a cohort study covering 1998 to 2018 found recorded autism diagnoses in the UK rose by 787%, especially among women and adults.

Autism spectrum disorder affects communication, social interaction and sensory experience, and is also associated with restricted interests and repetitive behaviour. But measuring how common it is is not straightforward. Scientists distinguish between diagnosed cases, the share of people who meet criteria in a uniform screening exercise, and the underlying biological incidence of the condition itself. Because there is no biological test for autism, most research depends on diagnosis records, which can be shaped by access to services, clinical practice and public awareness.

That helps explain why the apparent rise is not uniform across age groups or countries. In the US, the PubMed study found diagnosis rates were higher in girls and women than before, while the UK study found the increase was more pronounced among females and adults. AP has also reported that autism among US 8-year-olds continued to rise in 2022, reaching 1 in 31, up from 1 in 36 in 2020, with improved recognition and diagnosis cited as a major factor. Together, those findings suggest that many people, particularly women and older adults, are being identified later in life after years of missed or incomplete recognition.

Changes to diagnostic rules have also widened the net. Over time, revisions to medical manuals, including the addition of Asperger’s disorder in the 1990s and later changes to the autism spectrum concept, have expanded who can receive a diagnosis. Researchers have also described “diagnostic substitution”, in which children once labelled with intellectual disability or other developmental conditions are now more likely to be identified as autistic. In Australia, one recent study linked a public funding scheme to a 32% rise in reported autism prevalence, suggesting that policy and access to support can influence who gets counted.

The latest research from South Korea adds weight to the argument that better detection is a major driver. A study of 62,081 children using constant screening methods found autism prevalence of about 2% to 3%, but the proportion meeting criteria did not rise over 12 years. That pattern implies that in places where diagnosis rates are climbing, the change may reflect improved identification rather than a sharp increase in the number of children who are autistic.

Still, scientists do not rule out biological and environmental influences entirely. Studies continue to link autism risk with inherited factors, older parental age, maternal obesity, gestational diabetes and inflammation during pregnancy, while some environmental exposures may carry a small risk. Researchers also stress that vaccines are not associated with autism. The broader conclusion from the evidence is that the surge in diagnoses is being driven by a mix of better awareness, looser or shifting definitions, administrative incentives and changing social attitudes , all of which have made autism more visible, and sometimes more broadly applied, than in the past.