Adaptive Behavior Development and Autism Outcomes: A Comparison of Elevated- and Low-Likelihood Cohorts

Children born low-birth-weight (LBW) or with autistic siblings may show differences in their developmental trajectories, including higher rates of autism and lower levels of adaptive behavior skills. Parsing out developmental differences in these groups could help hone screening tools and lead to more precise interventions. The present study aimed to evaluate trajectories of adaptive behavior in children at elevated likelihood for autism and investigate whether trajectories differ for autistic and nonautistic children based on their likelihood group at birth. Two hundred fifty-seven children participated in a longitudinal study at approximately 7, 14, 28, and 39 months of age. Participants were categorized as low likelihood (LL) or elevated likelihood (EL) due to LBW or having an older autistic sibling. We analyzed diagnostic outcomes and social, communication, daily living, and motor skills as measured by the Vineland Adaptive Behavior Scales-Third Edition. Both EL groups presented with adaptive behavior delays, but children with an autistic sibling exhibited greater delays than their LBW or LL counterparts, particularly if they themselves were diagnosed as autistic, with some age- and domain-related nuances. Results reveal the unique developmental vulnerabilities among both EL groups and underscore the importance of targeted intervention during this critical early period.Lay AbstractSome children are more likely to develop autism than others or are more likely to have delays in their development. Babies who are born with a low birth weight and those who have an older sibling with autism are two examples. These children may also have more difficulty with everyday life skills like communicating, socializing, and taking care of themselves. This study followed children from about 7 to 39 months of age to see how their everyday communication, social, daily living, and motor skills developed over time. We found that children who had an older autistic sibling had the most difficulty with everyday skills compared with other groups and were more likely to develop autism themselves. These findings help us better understand how development differs among children who may go on to develop autism and can help us provide better interventions for these children early in life.