July 16, 2007

Learning to Diagnose Autism Spectrum Disorders

Picture of a little girl standing by the ocean

For children with autism, the sooner the disorder is identified and treated the better the outcome for the child. Now researchers report that it's possible to detect autism in some children as young as 14 months of age, the earliest the disorder has ever been diagnosed. In other children, the scientists didn't see definite signs of autism until later — by about 2 years old.

Autism spectrum disorders (ASD) include several related brain disorders, with symptoms spanning the spectrum from mild to severe. People with ASD have extreme difficulties with social interactions, communication and repetitive behaviors. The condition affects about 1 in 150 children, and it lasts a lifetime.

Most experts agree that early intervention — including behavioral therapies, specialized teaching and medication — can improve quality of life for years to come. Unfortunately, ASD is rarely diagnosed before age 3.

Dr. Rebecca J. Landa at the Kennedy Krieger Institute in Baltimore and her colleagues set out to study the progression of ASD in at-risk children to see if earlier diagnoses could be made. The research was supported by NIH's National Institute of Mental Health (NIMH).

As reported in the July 2007 issue of the Archives of General Psychiatry, the scientists studied 107 children considered to be at high risk for ASD because they had a sibling with the disorder. An additional 18 children with no family history of ASD served as the comparison group. The children's social and communication skills were repeatedly assessed beginning at 14 months until about 3 years of age.

By the end of the study, 30 of the high-risk children had been diagnosed with ASD. These children fell into two distinct groups. Half of them — called the early-diagnosis group — had dramatically lower social and communications abilities at 14 months of age than the other groups. The other half — the later-diagnosis group — were nearly indistinguishable from "normal" children at 14 months of age. However, by the time they were 2 years old, their social and communication skills declined and approached the lower scores of the early-diagnosis group.

These findings reveal two unique pathways that ASD may take during early childhood. While ASD can be distinguished in some children at just over 1 year of age, others appear to show only very subtle differences from normal development until after 14 months of age, when their skills begin to backslide.

The researchers note their findings may not be applicable to the general population, in part because all the children with ASD in their study had a familial risk. More research will be needed, with larger groups of children, to better understand the developmental patterns of ASD and to develop reliable tools for early diagnosis.

— by Vicki Contie

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