By Jenifer Goodwin
FRIDAY, April 23 (HealthDay News) -- Children with autism whose social and communications skills regress around age 3 tend to have more severe autism than children who show signs of the neurodevelopmental disorder at younger ages, new research finds.
Autism spectrum disorders are marked by delays or disruptions in social, language and communications skills, and restricted or repetitive behaviors or interests. Increasingly, doctors are coming to understand that there are several subtypes of the disorder, explained senior study author Dr. Paul Law, director of the Interactive Autism Network at Kennedy Krieger Institute in Baltimore.
In the study, researchers used data from 2,720 parents of children aged 3 to 17 years who had been diagnosed with an autism spectrum disorder. Children were placed in one of three groups, depending on how and when their autism symptoms started:
- Regressive, in which children seemed to be developing generally normally or close to normally, but then experienced a sharp decline in skills before age 3. About 44 percent of the children were in this group.
- Plateau, or the 17 percent of children who were not delayed or only mildly delayed until about age 2, at which point they gradually or abruptly stop developing.
- No loss/no plateau, sometimes called early onset autism, in which subtle signs of autism show up at relatively younger ages, but children don't regress or plateau. About 39 percent of the children fell into this category.
The researchers found some notable differences between the groups. In children who regressed or plateaued, parents said they first became concerned about their child's development at about 17 months, compared to about 15 months for children who did not plateau or regress.
Children who regressed said their first word at about 14 months, compared to 20 months for children who plateaued and 21 months for those with no loss/no plateau autism.
Another difference: Children who regressed took longer to potty train -- about 52 months, compared to about 48 months for other children with autism.
Over time, children who regressed tended to end up with more severe autism. They were at the greatest risk for not attaining conversational speech, and were more likely than the other groups to need educational support, such as a classroom aide. The more marked the regression, the more severe the autism later on, according to the study.
Autism with regression is much debated among researchers, with some estimates putting the prevalence at one-third to one-half of children with the disorder, with others saying as few as 15 percent of children experience regression.
Study author Luther Kalb, a researcher at the Center for Autism and Related Disorders at the Kennedy Krieger Institute, said some of the discrepancy may be definitions of regression -- some consider autism regression to be only children who had no symptoms of autism prior to the decline in previously acquired skills, while others allow for some delays prior to losing skills.
In the study, about 35 percent of parents had concerns about their child's development before their child began losing skills.
The study was published online April 20 in the Journal of Autism and Developmental Disorders.
"There are still discussions within the science community about how exactly to define regression," added Andy Shih, vice president of scientific affairs for Autism Speaks. "This study certainly adds to the body of evidence that suggests there is a differentiation between different types of autism development progression and outcomes for the individual."
Parents whose child has experienced regression should take heart, Law said, and remember that the statistics show trends, not how an individual child will do. "A lot of children with regression did well," Law said. "There is a lot of individual variation. This is by no means a very dire sentence."
Among the first signs of autism typically noticed by parents are lack of eye contact or social smiles, speech delays, restricted interests, hand waving or flapping, or generally not engaging with others in the ways other children do, Kalb said.