Weak Motor Skills at 6 Months may Show Early Signs of Autism

Previous studies have shown that certain repetitive behaviors seen in infancy can be early signs of an autism spectrum disorder (ASD). Now researchers from the Kennedy Krieger Institute in Baltimore, Md., have found that reduced grasping and fine motor activity among 6-month-old infants may indicate a similar issue. The study, published in the journal Child Development, shows how certain characteristics, or endophenotypes, may have a genetic relation to ASD that can further our understanding of the health issue.

"Among the infants with familiar history of ASD, many were shown to have reduced fine motor skills regardless of eventual ASD diagnosis," said Dr. Rebecca Landa, the lead study author and director of Kennedy Krieger's Center for Autism and Related Disoders, in a news release. "This means that reduced fine motor skills could be an ASD endophenotype without predicting full diagnosis. Identifying potential endophenotypes has important implications for future research and may improve our understanding of the neurobiology and genetics of ASDs."

To better identify potential endophenotypes, researchers conducted two experiments that examined the correlation of early motor development and object exploration in children at low risk (LR) or high risk (HR) of developing an ASD.

In the first experiment, researchers examined 129 infants, many of whom had a sibling with a confirmed ASD. Most of the participants were 6 months old and followed longitudinally till 36 months. Researchers used the Mullen Scales of Early Learning (MSEL), which determined assessment based on the following five categories: Gross Motor (GM); Fine Motor (FM); Visual Reception (VR); Receptive Language (RL); and Expressive Language (EL).

The participants were divided into four groups based on the results: low-risk (LR) infants without ASD; high-risk (HR) infants without an ASD, language or social delays; HR infants showing language or social delays but no ASD; and HR infants with autism or an ASD. Subtle differences between HR and LR infants who did not receive an ASD diagnosis  by 36 months suggests that lower fine motor skills on the MSEL are characteristic of infants with high familial ASD risk.

Researchers conducted a second experiment on a new group of 6-month-olds in both LR and HR categories, examining their natural grasping behaviors. Forty-two infants who had siblings with an ASD were observed in an unstructured play session.

Findings showed that reduced grasping of participants in the second experiment illustrated a similar pattern for those in the first experiment. However, researchers note that the results may not be entirely accurate due to the effect of gender in the LR sample.

With future studies, researchers said they hope to examine any preliminary findings that can help to more quickly determine early symptoms related to ASD.