Influence of siblings on adaptive behavior trajectories in autism spectrum disorder.

The study is observational and cannot establish causation; it is unclear whether siblings cause faster adaptive growth or if other factors associated with having siblings (e.g., family resources, social complexity) drive the difference. Attrition was higher among Black families, and the sample was predominantly White, limiting the generalizability of findings across racial groups. The sample was recruited over 28 years ago, so the level of early intervention and diagnostic practices may not reflect current standards. The finding regarding male siblings and gender match was based on a predominantly male participant sample (79.3%), limiting conclusions about females with ASD. Racial differences in adaptive growth trajectories were significant but likely confounded by socioeconomic factors such as caregiver education and family structure, which were not fully disentangled. The study used age-equivalent scores for adaptive behavior, which may obscure differences in rate of change compared to standard scores, though the authors justified this for participants with intellectual impairment.

The research was supported by N.I.H. grants. No specific commercial conflicts of interest or sponsor involvement in study design or manuscript writing are detailed in the provided text beyond the funding source.

Do not interpret the association between having siblings and faster adaptive growth as evidence that having a sibling causes better outcomes. The study is observational, and families with siblings may differ in other ways, such as socioeconomic status or social complexity, that could influence adaptive development. Additionally, the finding that male siblings were associated with steeper growth is preliminary and requires replication, particularly given the small number of female participants in the sample.