News The latest developments in autism research.

Alternative screen finds high autism prevalence in U.S. state

by  /  12 May 2017
School’s in: Researchers sent an autism screen to nearly every school in three counties in South Carolina.

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A new study in South Carolina has found a prevalence of 3.62 percent for autism, or roughly 1 in 28 children. Researchers presented the unpublished findings today at the 2017 International Meeting for Autism Research in San Francisco, California.

The study screened children born in 2004, the same birth year analyzed in the most recent prevalence estimate by the Centers for Disease Control and Prevention (CDC). For South Carolina, that estimate, released in 2014, reported a prevalence of 1 in 81 children1. The average prevalence for the United State is 1 in 68.

These striking differences stem from the fact that the researchers met many of the children to assess them for autism, instead of relying on existing assessments, says lead researcher Laura Carpenter, professor of pediatrics at the Medical University of South Carolina.

“I think this is probably getting pretty close to the true prevalence,” Carpenter says. “This is probably going to make a lot of sense for anybody who is working in a school or autism clinic.”

The new work is modeled after a similar prevalence study in South Korea that found an autism rate of 2.65 percent, more than twice the U.S. rate at that time.

It’s not surprising that the method the new study used yielded a higher prevalence rate even in a U.S. state, says Young Shin Kim, who led the South Korea study.

Two steps:

To assess prevalence, the CDC typically looks at the school and medical records of every child in a specific district. In the new study, by contrast, researchers sent an autism questionnaire to schools in three counties in South Carolina. The researchers then examined a subset of the children who screened positive, using several autism diagnostic measures.

The advantage of this approach is that it may pick up children who don’t have an official assessment of autism in their records. For example, a therapist might assess a child for a related condition, such as attention deficit hyperactivity disorder (ADHD), but not note any autism-related features, says Carpenter.

The downside is that the method does not look at every child in the region. The researchers sent the screen, the Social Communication Questionnaire, to 8,780 families from 123 of 127 schools in the region, as well as 25 home-school networks and 3 virtual schools. Fewer than half the families, or 4,185, returned the screen.

The researchers invited all 274 children who scored above the cutoff for autism for an in-person assessment. They also invited 584 children who scored in the borderline range. Of all these children, only 292, or 34 percent, agreed to participate.

Such a big drop-off in participation can skew the findings, says Maureen Durkin, professor of population health sciences at the University of Wisconsin, Madison, who was not involved in the study. For example, parents who are concerned that their child has autism may be more motivated to participate, she says.

“Unless you assume that those who didn’t participate have the same rate of autism as those who did, there is real potential for selection bias,” she says. “The one thing about selection bias is it’s by definition unknowable. I can’t say this is definitely an overestimate, because I really don’t know.”

Diagnosed subset:

Carpenter agrees that the low response rate is of concern but notes that the numbers could also go the other way. For example, families who already know their child has autism may not be motivated to take the time for yet another assessment.

What’s more, the demographic profile of the families who were sent the screen roughly matches that of the families who responded and those who came for the assessment — suggesting that the proportion who came for assessment are representative of the broader population.

This finding is “encouraging,” says Durkin. “That’s a strength.”

The study found that of the 292 children assessed in person, 52 children, including 7 girls, have autism, and 16 of them did not have a prior diagnosis. All but 2 of the 16 children had been diagnosed with other conditions such as ADHD or anxiety.

Of the 52 children, 21 percent have intellectual disability, lower than the CDC estimate of 32 percent. This may be because the new method is better suited to catching children with intelligence quotients of average or above, says Carpenter.

For more reports from the 2017 International Meeting for Autism Research, please click here.

  1. Christensen D.L. et al. MMWR Surveill. Summ. 65, 1-23 (2016) PubMed

8 responses to “Alternative screen finds high autism prevalence in U.S. state”

  1. Ethyl says:

    I think there is some confusion between autism and other “language disorders.” And so many kids, like my son, had a severe language disorder, but at age 4 the neurologist did not find it severe enough to be autism. Nevertheless, the school gave him a label of “educational autism”. He was echolalic to grade 4, although it was hard to tell because he used “scripts” that pretty much followed the conversation when he did talk. These were memorized words from t.v. shows, mostly. It was the only way he knew how to communicate.

    Looking back, it was his learning disabilities that made school most difficult, but because he had the label of autism, they weren’t addressed. This was starting 17 years ago. He ended up graduating from tech school as a machinist, and makes a good living. I would have never dreamed he would have made it that far. I was just looking to when he was diagnosed….in 1997 the prevalence was 1 in 500. Children who are far less handicapped are now being labelled. But I don’t think it is necessarily a reason to worry for their futures. We all carry a heavy load, and 1 in 5 kids have learning disabilities, many of whom I sincerely believe are now called autistic. Learning disabilities like dyslexia, dysgraphia, dyscalculia, dyspraxia…are difficult, but so common that most find ways to accommodate or even excel with the gifts they bring. Those that don’t are over-represented in the prison systems and suicides, sadly.

    While increasing the label may help, we should carefully consider if placing a label and medicating doesn’t place more of a burden on little shoulders.

  2. Xiaoyaya Autism-Initiative says:

    Well, is it possible that we expand the diagnosis so much that everyone has a little symptom will be autism? This can be scary that everyone will need service and those who really need will be ignored.

  3. Maurinemeleck says:

    My comment has been removed ??????????????????
    Vaccines can and do cause autism.

    • Ethyl says:

      Tell me why you think that. My son had an HHE at age 2 months. By the time I figured it out it may have contributed to his autism, he was 7 years old, 4 years to late for VAERS or NVICP. Science says it means nothing, but then again, they can’t tell me what happened. It’s a little tricky. Instead of looking at the child, they perform statistical analysis. But no one looks at a child who has had a reaction long term. They say, “there was no indication of brain damage.” following the severe adverse event. How can they know when they don’t look long term? Their lack of curiosity is kind of a clue that they don’t want to know.

      I can see all of you posts…3 of them?

      Okay, what I have been thinking is a a child has the measles and dies or has an encephalopathy, it is the end of the world. There is no “so-called” adverse event. It is not a coincidence…the parents are not looking for an excuse…It is not a ‘rare’ event. It is a hair on fire end of the world event.

      But if a child has an encephalopathy or dies following a vaccination, it is a coincidence. The parents are looking for something to blame (besides themselves). It is a rare occurence, and “these things just happen.”

      That’s where I am. I don’t believe beyond doubt that the vaccine caused my son’s learning disabilities. I know he inherited them from his birth mother…but it sure made school hell. I just can’t believe how science can be so sure about something they have never even studied in a personal way.

      • Maurinemeleck says:

        Hi Ethyl-Yes, there are a very small number of children that5 are born with autism-like 1 in 10,000 and he may have been one of them. But almost all of the children are not born with it. There may be a genetic predisposition and we call that the gun, but the trigger is the vaccines. Because the drug companies make billions and billions of dollars a year from vaccines, there is no concern for the health of our children. If you haven’t seen “Vaxxed” you should Can view it for about $2.99 on amazon. It’s about a CDC whistle blower that tells us how the gov ‘t health organizations lie about their vaccine safety studies. Vaccines are neither safe or effective. Lots of vaccine/autism groups on FB. The gov’t and drug companies know vaccines cause autism and other health problems, but they lie constantly. I’ve been fighting this for 17 years. BTW-they removed my long comment.

        • Ethyl says:

          I’ve been at it almost the same number of years, starting at age 7, my son is now 23. I really did believe science would tell me what happened…the HHE. To this day, I have no idea what caused it. Science has never looked. At least 20,000 kids had the same reaction since the NVICP/VAERS were established. “But let’s do another epidemiological study.” Scientist obsess over minutia about autism, doing studies on the weak cries of mice w/DiGeorge like syndromes the mother mice ignore….but when your child loses consciousness…it’s just an unfortunate occurrence.


          Too bad the “so-called” Hypotonic Hyporesponsive Episode was correlated with the vaccine–no scientist in their right mind would lose respect or their job by equating the two bearing any responsibility for brain damage. But if it happened following measles, they would shout if from the rooftops. Look at Thompson (?whistleblower) from the CDC. I think he must have had a nervous breakdown with his expose, or at least his peers would like him to think so. I am so amazed he is still employed.

          I won’t watch Vaxxed. I do believe vaccines have saved, world wide, millions of lives, and maybe thousands in the U.S. Offit’s work may, in time, save thousands of children. I have a friend who works as a nurse in the Democratic Republic of the Congo. Children die from diarrhea and lack of proper nutrition even though it used to be thought it was starvation. I don’t want that here. But consider, here in the US. I’ve taken 3 Immunology courses, and the professor gave credit to engineers over vaccines. We have clean water, adequate housing, access to improved health care, safer environments (fewer vectors of disease), and ~~~soap~~~. They have equally saved as many or more lives. That’s why the measles outbreak in Eastern Europe this year led to 17 deaths out of ~300 cases. That’s why we’ve have 3 deaths over the last decade in America. Thank God for engineers.

          But, I don’t think vaccines are nearly as perfect as they say. Look at these yahoos who are trying to tell me one in one million. OMG…that is so…….”truthy”, and has not a thing to do with the actual science. I won’t even bother to look up the WHO numbers. I could argue with them, but they are exactly like the anti vaccine zealots they demean. Minds like steel traps rusted closed.

          But I want to tell you I feel for you. And I understand exactly what you went through. You seem very reasonable. I’ll take reason over “rationality” any day. (I am so freaking tired of skeptics). What happened to your child is a shame. And science can’t tell you what happened because they are afraid to, I guess. So parents come up with their own ideas.

          This post will also be deleted. Every one I’ve ever mentioned vaccines in does get deleted. But you will still get my disqus post, I believe. Keep talking to me, if I haven’t run you off.

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