Autism is more common among children in England than previously thought, with rates higher among Black pupils than their white peers, researchers have revealed. Autism spectrum disorder (ASD) affects communication and behaviour and is thought to affect 1-2% of people around the world, with diagnoses more common among males than females. However, there has been little large-scale research into its prevalence, and whether it differs with ethnicity. Now researchers say an analysis of data from more than 7 million schoolchildren in England not only reveals ASD is more common than previously thought, but that there are striking differences in ASD prevalence around the country, and between different groups. “This is the largest prevalence study to date in the world,” said Dr Andres Roman-Urrestarazu of the department of psychiatry at the University of Cambridge and a co-author of the new research. Writing in the journal Jama Pediatrics, Roman-Urrestarazu and colleagues reveal how they analysed data from the 2017 spring school census obtained from the national pupil database in England to determine the prevalence of ASD among schoolchildren aged five to 19 in state-funded schools in England. This census records whether children have received a diagnosis of ASD through local authorities and the NHS, or have been flagged as having ASD through a school assessment. The results reveal that 119,821 pupils had ASD, of whom 21,660 had learning difficulties. When adjusted for age, sex and other factors, the team say that equates to 1.76% of schoolchildren in England having ASD – a higher figure than the 1.57% suggested by an earlier, smaller study carried out by the team. The rise, they add, is likely down to improved recognition of ASD. However, prevalence was not uniform. As with previous studies, ASD was found to be more common in boys and men than girls and women, with the study revealing that ASD to be almost four-and-a-half times more common among the former than the latter. But there were geographical differences, with the team finding an ASD prevalence of 3.38% in Solihull compared 0.63% in the Cotswolds, while in some local authorities the male-to-female ratio for ASD was almost 13:1 – a figure Roman-Urrestarazu said suggests some areas might be overlooking autistic women. There were also striking ethnic differences, with ASD most common among Black pupils, of whom 2.11% found to have ASD, and lowest in Roma/Irish Traveller pupils, of whom 0.85% had ASD. Among white pupils, the figure was 1.84%. The study has limitations, including that it might understate the number of children who have ASD, only covers data from state-funded schools, and cannot prove cause and effect. However, Roman-Urrestarazu said the study is not only important for helping local authorities to plan ASD support services, but also flags disparities in prevalence that are cause for concern. While he said more research is needed to explore the causes for the variations, Roman-Urrestarazu noted a number of factors could be at play, including individuals’ access to diagnosis or recognition of symptoms, bias in diagnosis, local authority budgets and other issues – for example, he said, it is known that problems such as psychosis are more common among recent immigrants, meaning the same may be true of other conditions, including ASD. The team found social disadvantage to be one important factor, with children eligible for free school meals around 60% more likely to have ASD. Indeed, the team say more than 12% of the increased ASD prevalence in Black children was explained by differences in racially linked social disadvantage compared with white pupils. Prof Uta Frith, an expert in autism from University College London who was not involved in the work, praised the size of the study but said the mechanism by which ethnicity might be linked to ASD is unclear. But she said that the link to deprivation highlighted by the study raises concerns, given that the Covid pandemic has exacerbated inequalities and the disparities shown by the study might be expected to become worse. “[Deprivation] is such a major factor,” she said.