Differences between typically developing children and those with an autism spectrum disorder are detectable by age 2, potentially allowing for earlier intervention, according to a report in the Journal of Child Psychology and Psychiatry. Rebecca Landa, PhD, Director of the Center for Autism and Related Disorders at the Kennedy Krieger Institute in Baltimore, and Elizabeth Garrett-Mayer, PhD, Assistant Professor of Oncology Biostatistics at Johns Hopkins University in Baltimore, examined 87 infants—from both high-risk groups (siblings of children with autism) and low-risk groups (no family history of autism)—at ages 6, 14, and 24 months. Development was evaluated using the Mullen Scales of Early Learning (MSEL)—a standardized test that assesses the gross motor, fine motor, visual reception, repetitive language, and expressive language domains of development—plus the Preschool Language Scale, the Autism Diagnostic Observation Schedule (ADOS), and the MacArthur Communicative Development Inventory. Using data at 24 months, as well as clinical judgment, the researchers categorized the infants as being unaffected, as having an autism spectrum disorder, or as having delayed language.

At age 6 months, no statistically significant differences were detected among the infants; at age 14 months, infants classified as having an autism spectrum disorder performed significantly worse than those classified as unaffected on all scales except the visual reception domain of the MSEL; and by age 24 months, children classified as having an autism spectrum disorder performed significantly worse than unaffected children on all domains and worse than language-delayed children on the gross motor, fine motor, and receptive language domains of the MSEL.

"The developmental trajectory of the autism spectrum disorder group was slower than the other groups’, and showed a significant decrease in development between the first and second birthdays," said Drs. Landa and Garrett-Mayer.

STABILITY OF DIAGNOSES AS CHILDREN AGE

In a related study published in the June Archives of General Psychiatry, Catherine Lord, PhD, and colleagues reported that the stability of autism spectrum diagnoses made at age 2 was very high through age 9. Dr. Lord is the Director of the University of Michigan Autism and Communication Disorders Center in Ann Arbor.

The study included a total of 192 children referred for autism assessment to state-funded community autism centers or a private university autism clinic and 22 controls with developmental delay; of the 214 participants, 172 were also assessed at age 9. Standardized instruments including a parent interview—the Autism Diagnostic Interview–Revised—and the ADOS, as well as clinical judgment, were used to determine a diagnosis of autism spectrum disorder at ages 2, 5, and 9.

The researchers found that agreement between autism diagnoses at ages 2 and 9 was 67%, "with the majority of change associated with increasing certainty of classifications moving from autism spectrum disorder/pervasive developmental disorder not otherwise specified (PDD-NOS) to autism." They noted that only one of 84 children with a diagnosis of autism at age 2 received a non–autism spectrum diagnosis at age 9, while more than half of children initially diagnosed with PDD-NOS met diagnostic criteria for autism at age 9. "Classifications changed substantially more often from ages 2 to 5 years than from ages 5 to 9 years," said the researchers. In addition, clinical judgment of autism at age 2 was a better predictor of diagnosis at age 9 (odds ratio, 12.8) than parent interview (odds ratio, 6.6) or observation (odds ratio, 6.8).

THE EARLIER THE DIAGNOSIS, THE BETTER

"Having a way for experienced clinicians to acknowledge their uncertainty about some 2-year-olds was ultimately helpful as a means of flagging children who by age 9 years had a range of difficulties from autism to very mild social deficits," said Dr. Lord’s research team. They also pointed out that "health care professionals should be wary of telling parents that their young children do not have autism, only PDD-NOS."

Dr. Landa commented, "If we are able to educate professionals to identify red flags in development, we can then recognize and diagnose the disorder at 1 1/2 or 2 years of age, instead of 3 or 4, allowing for earlier intervention and ultimately better outcomes." She concluded, "Introducing behavioral interventions even one year earlier can make a tremendous difference in the lives of children with autism and their families."

—Karen L. Spittler

Suggested Reading
Landa R, Garrett-Mayer E. Development in infants with autism spectrum disorders: a prospective study. J Child Psychol Psychiatry. 2006;47:629-638.
Lord C, Risi S, DiLavore PS, et al. Autism from 2 to 9 years of age. Arch Gen Psychiatry. 2006;63:694-701.

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