a boy with a toy footballInfants with an increased familial risk for autism exhibit developmental delays in motor skills, reports a study from the Kennedy Krieger Institute in Baltimore. These high-risk infants scored within typical ranges on developmental assessments, but in an unstructured play environment, they lagged behind their peers who had a low risk for autism. The findings indicate that infants with a family history of autism spectrum disorders (ASD) may have developmental delays even if they do not have autism themselves.

The researchers conducted two experiments with infants at a high risk (HR) and a low risk (LR) for autism. The HR infants were from families with a history of ASD. The two experiments compared how infants at a high and low risk for autism develop motor skills.

The first experiment consisted of 129 six-month-old infants who were mostly siblings of children with an ASD diagnosis. The researchers studied the infants longitudinally, following their progress through 36 months of age. Using the Mullen Scales of Early Learning (MSEL), a battery of tests that includes evaluations in gross and fine motor skills, language acquisition, and visual abilities, the researchers evaluated the infants’ development.

Based on the results of the first experiment, the researchers divided the infants into four categories: LR infants without ASD, HR infants without ASD or other delays, HR with language or social delays but without an ASD diagnosis, and HR with an ASD diagnosis. Despite the differences between groups, all the infants scored in the typical ranges on the MSEL. This led the researchers to conduct a second experiment.

For the second experiment, the researchers observed a different group of low and high risk six-month-old infants. These children participated in an unstructured play situation. The researchers found that the high risk infants did not exhibit the same level of motor competence as the low risk infants. The HR children demonstrated reduced grasping and object-exploration activity.

“Among the infants with familial history of ASD, many were shown to have reduced fine motor skills regardless of eventual ASD diagnosis,” said Dr. Rebecca Landa, lead study author and director of the Kennedy Krieger’s Center for Autism and Related Disorders.

The results have implications for understanding autism spectrum disorders. A developmental delay in exploration-related motor skills may be genetically related to ASD even though it is not, on its own, indicative of an autism diagnosis. The findings may help researchers learn more about the genetics of autism.

This research is published in the journal Child Development.

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