An editorial in Psychological Medicine argues the current autism spectrum has become so broad that one diagnosis now covers people needing lifelong care and adults living independently, reducing its clinical usefulness.
Frith says that breadth can steer clinicians toward autism when anxiety, ADHD, depression, trauma or language difficulties may better explain a person's problems, risking the wrong treatment or missed support.
UK autism prevalence has climbed from about 4 in 10,000 children in the 1960s to roughly 1 in 57 in a later study of more than 7 million schoolchildren, a rise she says improved recognition alone may not explain.
The UCL researcher, who has studied autism for more than 50 years, points to widening criteria, self-diagnosis, social media and neurodiversity debates as forces reshaping how autism is identified and understood.
Frith proposes clearer subgroups and support based on detailed individual needs rather than a single label, with greater priority for people with the most substantial disabilities.