Cognition and behavior: Autism symptoms change over time
Siblings of children with autism who are later diagnosed with the disorder themselves become more active, less adaptable and less likely to approach others over time, according to a study published 3 July in the Journal of Autism and Developmental Disorders1.
The results reinforce the observation that autism symptoms evolve as children age, the researchers say.
Autism is diagnosed starting at 2 years of age, but some indications may appear before then. To look for these early signs, researchers are studying the infant siblings of children with the disorder. These so-called baby sibs are about 20 times more likely to develop autism than the general population.
The researchers looked at parent reports of temperament for 54 baby sibs at 6, 12, 18, 24 and 36 months of age. Measures of temperament include how adaptable and active the children are, and how readily they approach others.
At 36 months, the researchers diagnosed some children with autism, some as typically developing and some as having developmental issues that do not meet the criteria for autism.
Parents did not always return questionnaires and so the number of children assessed is different for each age group. The number of children who developed autism ranges from 10 to 16 across the age groups, and those who developed typically from 7 to 27.
The children later diagnosed with autism are more adaptable than typically developing baby sibs at 6 and 12 months of age, but less so at 24 and 36 months. Similarly, baby sibs with autism are more likely to approach others than typically developing baby sibs are at 6 months of age, but less likely to do so at 24 and 36 months of age.
The baby sibs with autism are also less active than typically developing ones at 6 and 12 months of age, but similar at 24 and 36 months.
News and Opinion articles on SFARI.org are editorially independent of the Simons Foundation.
1: Del Rosario M. et al. J. Autism Dev. Disord. Epub ahead of print (2013) PubMed