Autism is just as common among adults as it is in children, a new study suggests, calling into question claims of an autism epidemic.

Many autism advocates have spoken of an epidemic in recent years as increasing numbers of children are diagnosed with the developmental disorder. But research out of England this week indicates that just as many adults have autism, though many go undiagnosed.

In a survey conducted across England, researchers found autism prevalence to be steady at about 1 percent for adults, according to findings published in the May issue of the Archives of General Psychiatry. That’s much the same as previous estimates for children in both the United States and England.

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Unlike prior research efforts which asked adults to self-report any autism diagnosis, this survey used a questionnaire designed to assess whether or not an autism diagnosis was appropriate. Then, 618 of the study participants took part in an in-person screening.

None of those in the study had previously been evaluated for autism, but ultimately the researchers found that 19 had the disorder. Age did not appear to be a factor, but men were far more likely than women to have autism.

“To our knowledge, we have demonstrated for the first time in the general population that the rate of ASD is not significantly associated with age, suggesting that the causes of autism are temporally constant,” wrote Traolach Brugha of the University of Leicester and his colleagues, though they noted that further research is necessary to confirm their findings.