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Regression may mark one-third of autism cases

by  /  27 September 2012

About one in three children with autism abruptlylose language, social or other developmental skills in their second year of life, according to a meta-analysis published 2 August in the Journal of Autism and Developmental Disorders1.

In contrast to most children with autism, who either develop normally and then plateau or display signs of the disorder from birth, this subset of children appears to develop normally early on and then suddenly regress.

The results come from the synthesis of 85 studies published between 1980 and 2010 that examined regression, and include nearly 30,000 participants diagnosed with an autism spectrum disorder.

“I see regression more as part of a continuum,” says Audrey Thurm, a staff scientist at the National Institutes of Health in Bethesda, Maryland. But it’s still important to determine how common it is, she adds.

Perhaps as a result of this disagreement, estimates of regression vary widely, ranging from 13 to 50 percent of all autism cases2,3.

“We found pretty clear evidence that how researchers defined regression made a big difference,” says senior investigator Jonathan Campbell, professor of educational, school and counseling psychology at the University of Kentucky in Lexington. ”I think one of the main contributions that we’ve made in this paper is to emphasize that we need to think carefully about how we’re going to define regression.”

The researchers divided the studies in their analysis into four types, based on the way those studies define the phenomenon: language regression, language and social regression, mixed and unspecified. (Mixed regression is defined as a loss of language, social and other abilities, such as daily living or motor skills.)

Taken together, the overall prevalence of regression is 32 percent, the researchers found. When they limited the studies in their analysis to those that only looked at the loss of language, the rate fell to 25 percent. The prevalence was highest, at 39 percent, for unspecified regression, the broadest definition of the term.

The mean age of regression, based on the 24 studies that included that information, is 21 months.

Regression debate:

The regression rate reported by the new analysis is probably an underestimate, because of the way the individual studies were conducted, says Sally Ozonoff, professor of psychiatry and behavioral sciences at the University of California, Davis MIND Institute, who led one of the studies included in the analysis.

Social regression, in particular, may be more common, Ozonoff says, because more of the studies in the analysis looked at language only, rather than at social skills alone.

“I think the definition of regression — whether that’s what the studies used or not — ultimately has to be related to social abilities, because social deficits are the core of autism,” she says.

One of the major challenges in studying regression is that researchers often rely on parents’ memories to establish whether a child experienced a loss of skills years earlier. Many developmental changes are subtle and gradual, making it difficult for professionals, let alone parents, to notice and pinpoint them in time.

A more recent approach to studying regression is prospective, which involves following children who are at high risk for autism to see whether and when they lose skills. Those studies are time-consuming and expensive, however, and only 2 of the 85 studies in the meta-analysis used this approach.

One of the two studies, led by Ozonoff and published in 2010, provides strong evidence that parents underestimate regression. Compared with the 17 percent regression rate as reported by parents, Ozonoff’s team found that 86 percent of the children showed a decline in social skills.

What’s more, the study found that children begin to lose their social skills as early as 6 months of age — more than a year before the average age reported in the meta-analysis.

“Parent report is probably catching the tip of the iceberg,” says Ozonoff. “When we use other research techniques, we realize that a lot more children have regression.”

Pinning down the prevalence of regression is important because it provides a benchmark for a child’s trajectory. It may also affect how well a child fares over the long term.

“The real meaningful question for me is, does it make a difference if a kid experiences developmental regression or not?” says Campbell, who plans to analyze the relationship between regression and developmental outcome.

Some studies have found that children who undergo regression fare worse, than those who don’t, but other studies have found no difference4. Sorting out the prognosis might allow parents and pediatricians to intervene and improve their quality of life.


1: Barger B.D. et al. J. Autism Dev. Disord. Epub ahead of print (2012) PubMed

2: Rogers S.J. Ment. Retard. Dev. Disabil. Res. Rev. 10, 139–143 (2004) PubMed

3: Stefanatos G.A. et al. Neuropsychol. Rev. 18, 305–319 (2008) PubMed

4: Werner E. et al. J. Autism Dev. Disord. 35, 337-350 (2005) PubMed

  • Laurie

    My son showed regressive symtoms. He was developmentally on task until about 18 months of age, albeit quirky with some sensory issues. He began to selectively speak to people, then barely at all. He also lost some fine and gross motor functioning and definitely began to socially isolate himself; gone were the hugs and spontaneous kisses. Ever since we have had to steal kisses on the arms and appreciate our sideways hugs. He is now 12 and, while we have seen great improvements, I’m not sure that he will ever be as socially and emotionally available as he was prior to his regression.

  • Sarah

    Regression definitely happens. My son regressed into autism at around 18 months. It was a slow deterioration, loss of skills and language. In hindsight, I remember he had loose bowel movements as a baby which may have been an early warning sign of an immune dysfunction. He was otherwise on track developmentally up until he regressed at 18 months. He is now 8 years old. I also notice that he has smaller regressive episodes since then that I feel is being triggered wither by diet or stress. I think regressions need to be studied more in relation to GI issues, abnormal gut microbiome, inflammation in the GI and brain, immune dysfunction.

  • Katie Wright

    I am thrilled to see SFARI reporting on this study.
    It is very frustrating to constantly here that “autism develops in the womb,” when one’s child developed perfectly for years. We must study the environmental factors that trigger these regressions, or else this will just continue to happen. According to an IAN study, sadly, severely regressive children, have the worst long term prognosis- even with quality interventions. I know this to be true with my son. Regressive autism, more often than not, is a biological syndrome affecting the gut and immune system.
    We need to move away from this idea that autism is only about the brain or synapses.
    Recent breakthrough research on the influence of gut microbiota in autism is key. Jyonuchi and MacFabe have done some wonderful work on this sub group.

  • jab

    look toward exposures to things that shift the immune system toward the TH2 immune system —you may find your answer there. FYI bisphenol A , MSG are 2 of those chemicals.Those chemicals are everywhere. Probably others as well– it would be interesting to see a study of the BPA levels in asd kids who regress compared to those that dont ….

  • jab

    also they should look at the child’s mitochondrial health . ASD kids (alot of them) have quite specific mitochondrial issues related to the electron transport chain ccomplexes/function and increased ROS production within the mitochondria…..just my thoughts. gut microbiota probably issue as well.

  • jab

    fyi — TH1 system is needed for proper neuronal pruning —– when really TH2 shifted then cannot do proper neuronal pruning and that may be why the kids regress.

  • Kathy

    My son has regressed at age 14 with his daily living routines. He will stand in the bathroom for hours unless I turn the water on for him, and when he is done brushing his teeth he will come get me to turn off the water. He has to have me buckle his seat belt or else he won’t get out of the car unless I buckle it then unbuckle it plus open and close his door each time we go somewhere. Lately I have been so frustrated with him because he won’t leave the house on time for school. Today he took the bus home from school and as I was going to my car to go pick him up from school I saw him in the middle of the street standing there like he was waiting for a bus or something. I ran out there yelling his name and no response. I was proud of him for taking the bus but why stand in the street? He is non verbal and he even asks me to take off his glasses before he goes to bed, if I refuse he will call my name my real name not mom, over and over until I go in his room. He was doing so well and now this has got me dumbfounded. Is it manipulation? or is he trying to bring me into his world which I can’t go into. He has to talk to me about how he feels and I will help him but this behavior has to stop, is he afraid to grow up? I get mad and I think about it later and feel sad. I have no idea what to do. Has anyone ever experienced this with their child?

    • Ella

      Kathy I have never heard of regression that late in life. I get mad at my son too and feel bad. Is there anything newly introduced into his diet or his life that would make him regress? It’s a hard life for them and us 🙁 hang in there.


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