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Children With Autism Developmentally Normal at 6 Months

In Autism Spectrum Disorders, Neuropsychology, School Psychology, Special Education on Tuesday, 6 November 2012 at 15:24

Children With Autism Developmentally Normal at 6 Months

Pam Harrison

Infants who go on to develop autism spectrum disorder (ASD) are developmentally normal by the age of 6 months, and the earliest signs of developmental disruption are subtle and not specific to autism, prospective, longitudinal data show.

In the largest prospective, longitudinal study to date comparing children with early and later diagnosis of ASD with children without ASD, Rebecca Landa, PhD, Kennedy Krieger Institute, Baltimore, Maryland, and colleagues found that the earliest signs of developmental disruption in children with ASD are likely to be nonspecific to ASD, such as communication or motor delay.

At 6 months, development within both the early-onset ASD children and those with later-onset ASD was comparable both to each other and to non-ASD control children.

“The standard clinical tools that we use to assess early development are not identifying abnormalities in babies midinfancy that go on and have autism,” Dr. Landa told Medscape Medical News.

“So the assumption that any infant who is going to have autism would be obviously autistic in midinfancy is a myth because this just isn’t happening.”

The study was published online October 30 in Child Development.

Developmental Trajectory

Studying the developmental trajectory of multiple systems — motor, cognitive, social, and language — in the first 3 years of life in children with and without ASD could shed light on the susceptibility of the developing brain to the impact of genetic, epigenetic, and environmental factors in children with ASD.

Therefore, the investigators examined language and motor development in children aged 6 to 36 months and social development from 14 to 24 months, the time during which ASD regression usually occurs.

Participants included 204 infant siblings of children with autism as well as 31 infants with no family history of autism.

The Mullen Scales of Early Learning provided measures of motor and language functioning, and the Communication and Symbolic Behavior Scales Developmental Profile provided measures of 2 social functions related to the diagnostic criteria for ASD.

By 14 months, the early-onset group exhibited significantly lower expressive language and shared positive affect scores than the later ASD group (P < .001 for both endpoints).

By 18 months, the early ASD group also had greater delays in receptive (P < .001) and expressive language development (P = .001) compared with the later-onset group.

Gap Closes

At 24 months, however, “the gap between the Early- and Later-ASD groups had closed, and no differences from the Later-ASD group were detected at subsequent ages,” the investigators write.

These findings indicate that the early-ASD group manifested earlier development disruption, especially as it affected language and social functioning, than children with later-onset ASD but that they were no more severely affected than later-onset ASD children at either 30 or 36 months.

“There are different developmental pathways to ASD,” said Dr. Landa.

Children who manifest symptoms by their first birthday are more globally impaired at 14 months than children who have later manifestations of ASD.

On the other hand, children with later-onset ASD do have some signs of developmental delay at 14 months, but these signs are not specific to ASD and include motor and communications delays.

However, by 36 months, both groups are comparable in their social and developmental characteristics, she added.

“Many pediatricians screen for autism at around 18 months, as the American Academy of Pediatrics recommends, but they don’t continue screening after that,” Dr. Landa said.

“But screening should be repeated through early childhood, and if concerning signs of delay associated with ASD are observed in a child who scores normally on standardized tests, further assessment is warranted.”

Need for Early Intervention

Deborah Fein, PhD, University of Connecticut, in Storrs, told Medscape Medical News that it is important to appreciate that the ASD children included in this study were infant siblings of children with ASD.

As such, “this is not the population at large, so these findings might not be generalizable,” Dr. Fein said

On the other hand, infant siblings of children with ASD are a small enough population that they could be followed very closely throughout their preschool years, and subtle delays in motor or social communication development could be identified.

Other children at risk for ASD, including premature infants or infants who have had obstetric complications, are also at risk for ASD and could be similarly followed, she added.

“There are preclinical signs of ASD, but in a sense, it doesn’t matter because if you know a child has some mild delay in cognitive or motor or social communication function, you still want to deliver early interventions,” she said.

“Then if full-blown autism does emerge, you’ll be on top of it.”

The authors and Dr. Fein have disclosed no relevant financial relationships.

Child Dev. Published online October 30, 2012. Abstract

Retrieved from: http://www.medscape.com/viewarticle/773990?src=nl_topic

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