Developmental Trajectories of Adaptive Behavior from Toddlerhood to Middle Adulthood in Autism

Background: Adaptive behavior skills are a significant predictor of adult outcomes. However, few studies have examined developmental trajectories in autistic individuals from early childhood into mid-adulthood and how these trajectories are associated with adult outcomes. Methods: This study uses a longitudinal sample ( n = 266) to investigate age-related adaptive behavior developmental growth trajectories across ages 1–55 years. The study investigated clinic records, including questionnaires, interviews, and diagnostic assessments. Caregivers completed the majority of questionnaires. Results: A linear spline model best fits the data, suggesting that from early childhood to young adulthood (ages 1–20; autistic individuals gained adaptive behavior skills, but scores declined from young adulthood to mid-adulthood [ages 21–55]). Higher IQs and fewer clinician-endorsed autism characteristics across childhood into mid-adulthood were associated with greater adaptive behavior skill growth over time. Caregiver reports of a higher quality of life and daily living skills in adulthood were related to adaptive behavior growth over time. Conclusion: Overall, the growth of adaptive behavior skills is positive from young childhood to young adulthood but begins to decline during adulthood. It appeared that there was a potential decline in adaptive behavior towards mid-adulthood. Results confirm the importance of adaptive behavior in caregiver perceptions of quality of life for autistic adults and suggest adaptive behavior is essential to support throughout the lifespan.