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A study released on Wednesday says that the new diagnostic criteria from the DSM-5 — often referred to as psychiatry’s diagnostic “bible” — could lower the prevalence of autism-spectrum-disorder cases.

In the new study, which was conducted by the Centers for Disease Control and Prevention (the CDC is responsible for national autism surveillance) and autism groups, the authors analyzed how the new criteria, in place since last May, would affect a population of 6,577 8-year-olds who are part of a large network of children with autism-spectrum disorder as defined by the prior DSM-4 criteria.

Applying the DSM-5 criteria, they discovered that the prevalence of autism-spectrum disorder in 2008 would have been 10 per every 1,000 people compared with the 11.3 per 1,000 people who were diagnosed with the DSM-4 criteria. Therefore, not all of the kids who were previously diagnosed with autism-spectrum disorder would meet the new criteria; in fact 81% of them would.

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That could have implications for families who relied on the diagnosis in order to benefit from services provided by states and schools for affected children. Even before they were finalized, the criteria outlined in the DSM-5, released by the American Psychiatric Association (APA) stirred controversy within the autism community for just this reason: the new guidelines removed subgroups of autism, such as Asperger’s and other milder forms of autism, and blended them into a single diagnosis of autism-spectrum disorder. The new code, the APA’s DSM committee felt, more accurately reflected clinical cases of autism and would help doctors to make more reliable diagnoses.

“The hope behind the new criteria is that it better reflects what autism is than what DSM-4 did. It’s not that DSM-4 isn’t good, it’s that what we had before was a grab bag, where you could have a little bit of this and a little bit of that,” says Catherine Lord, the director of the Center for Autism and the Developing Brain and a member of the DSM-5 committee. “What DSM-5 is trying to do is say there are common dimensions among people with autism that may be manifested in different ways. You may see something different in a child of 2 than you do in a person at age 35. But they share, for example, things like deficits in nonverbal communication.”

But when they were released, many experts worried that the new diagnosis would no longer apply to some children who formerly fit the definition of an autism-spectrum disorder. Therapies and care for autistic children can be expensive, and the diagnosis determines some families’ eligibility for these services.

(MORE: Mental-Health Researchers Reject Psychiatry’s New Diagnostic ‘Bible’)

On the other hand, Lord says it’s possible that other people who didn’t previously receive a diagnosis of an autism-spectrum disorder may now qualify under the new criteria, since it takes into consideration new factors such as a child’s behavioral history. “This means, you don’t have the behaviors now, but you’ve had them in the past. So, you would think that it would be actually easier to get a diagnosis of autism-spectrum disorder,” she says. “The point here is that if no one asked you about your history, you’re not going to have it in the record.”

One thing the study did not measure was the change in cases of a new disorder identified in the DSM-5 called social-communication disorder. It involves individuals who have deficits in social and communication skills, but don’t display the restrictive and repetitive behaviors typical of autism. Previously, these people likely would have been diagnosed with an autism-spectrum disorder, for lack of a more appropriate diagnosis. “Based on evidence we have seen to date, we think a lot of those individuals who no longer meet autism-spectrum-disorder criteria, meet social-communication-disorder criteria. But that shifts [concern] to whether people get access to services, whether they have a social-communication-disorder diagnosis or an autism-spectrum-disorder diagnosis,” says Michael Rosanoff, the associate director of research at Autism Speaks, an autism-advocacy organization.

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That’s important, he says, since there are currently no clinical guidelines for treating social-communications disorder, as there are for autism. “We understand that some individuals are being diagnosed with the DSM-5 and receiving a social-communications-disorder diagnosis. What we are unsure of is whether they are getting access to services that they can benefit from,” says Rosanoff.

So far, say autism-advocacy groups, previous diagnoses of autism under the DSM-4 are still recognized by schools and states that provide services for the disorder, and anyone who had a diagnosis of autism or Asperger’s before the DSM-5 does not need to get re-evaluated.

But they are concerned about how faithfully this designation is being executed. Currently, Autism Speaks found a mixed bag of responses, based on an unscientific survey of families who have undergone an evaluation with the DSM-5 about their experience. A small percentage of families reported that insurance companies and schools asked them to get themselves or their children re-evaluated under the new criteria. So while it’s not supposed to happen, there is evidence that it is. “What’s more troublesome is that some people are saying that with the new criteria, they are losing the new diagnosis, getting a social-communication-disorder diagnosis, and losing access to services,” says Rosanoff.

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In anonymous responses provided to TIME by Autism Speaks with the writers’ permission, one mother recounted how a regional center that funds services for her son who was originally diagnosed with Pervasive Developmental Disorder–Not Otherwise Specified (PDD-NOS) — which used to be its own category along the autism spectrum — asked for him to be re-evaluated, instead of folding him into the new autism-spectrum-disorder categorization.

Another survey responder says:

After fighting for a referral for two years, my son had his evaluation. They said he has the characteristics of an Asperger’s child, but there were new diagnosing criteria, and because of that he was either autistic or not. Because he’s verbal and has good cognitive skills, he cannot be diagnosed with autism … Even after 15 minutes of video showing him … hand-flapping, clapping, spinning, having meltdowns, they said they can’t diagnose because of the changes. Very frustrating. Now off to a second and third opinion. Whatever it takes to get my son the help he needs.

While these are anecdotal reports of challenges that parents are now facing under the new criteria, they suggest that a more scientific look at how the changing definition of autism is affecting the community is needed. “We need a better sense of what families are experiencing, and this should be a top priority,” says Rosanoff.

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