New information on emerging signs of autism

Elizabeth McBreen


Symptoms of autism generally do not begin to appear until after six months of age, and they emerge slowly over time rather than occurring rapidly. These are the results of a new study out of University of California, Davis.

The study, A Prospective Study of the Emergence of Early Behavioral Signs of Autism, compared the behavior of 25 siblings of at least one child with autism to 25 typical children with no known risk of developing autism. The research was conducted over the course of five years. Each child was studied at their regular well-visits at age six months, 12, months, 18 months, 24 months, and 36 months. After the six month visit, there was a clear divergence in the behavior of 86 per cent of the children who went on to be diagnosed with an autism spectrum disorder.

Lead researcher Sally Ozonoff, Ph.D., is the Vice Chair for Research in the Department of Psychiatry and Behavioral Sciences at the UC Davis Medical Investigation of Neurodevelopmental Disorders (MIND) Institute. Ozonoff says that each baby underwent the same series of development assessments, including the Mullen Scales of Early Learning. The assessment is a standard test used to track development that can be scaled for different ages. The tests were videotaped, and each instance of a smile, vocalization, and eye contact were scored. The examiners were not aware of whether each child was part of the high or low risk group.

Ozonoff says that some of the findings of the study fit right in with what parents have previously told researchers. “Overall, information from parents was accurate, but it’s much easier to remember big picture things. It’s very difficult to remember exactly what a child was doing at six months of age,” says Ozonoff. “This is the first study that quantifies these activities. We have exact counts of incidences.”

The study is significant, says Ozonoff, because it allows researchers to hone in on when signs of autism are emerging. This information is critical to improving the process of screening and diagnosis. Although there are children who show signs of a developmental problem prior to six months of age, Ozonoff says they are a small group. “Seeing signs at six to 12 months is still pretty early. If we can start to diagnose children at 12 to 18 months, that will be early.”

Another significant finding is that symptoms continue slowly emerging over time until about three years of age. Currently, American Academy of Pediatrics (AAP) guidelines recommend children be screened for autism twice in the first two years of life. Ozonoff says she would continue that practice, but add another screening after 24 months.

Susan Hyman, M.D., SAAP, is an AAP Fellow and Division Chief of Neurodevelopmental Disabilities at Golisano Children’s Hospital in Rochester. Hyman says that in addition to the two formal screenings recommended at 18 and 24 months, the AAP recommends ongoing surveillance for developmental problems during all well visits. A third formal screening is also recommended by AAP guidelines, according to Hyman, but many insurance policies do not cover it. “Ongoing assessment is important,” says Hyman, “because some developmental problems such as Asperger’s Syndrome often do not become apparent until school age.”

Because the study does not address causality Ozonoff says it cannot be used to directly refute a theory of causation, either genetic or environmental. The majority of childhood vaccinations are given during the first year of life, and Ozonoff says the results “cannot be used to refute the vaccine theory.” She adds though, that not every genetic problem is apparent at birth. “Just because something onsets later does not mean that it is not genetic. People are born with Rhett’s syndrome, but it does not show up until after six months. A language delay is present at birth, but does not show up until later. That doesn’t necessarily mean it is environmental.”

Courtesy of Spectrum Publications


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