Cascading effect of early sensory differences on subsequent autistic traits in infants later diagnosed with autism: a prospective cohort study
Sensory differences constitute core diagnostic features of autism. The cascading effect model posits that early sensory differences may be prospectively associated with subsequent autistic traits, whereas empirical evidence in infancy remains scarce. This study aims to characterize trajectory differences of early sensory profiles and examine the cascading effect on subsequent autistic traits in infants later diagnosed with autism. In this prospective longitudinal study, 134 Chinese infants were followed from 12 to 36 months of age. Trajectory differences in four sensory profiles (sensitivity, avoiding, registration, and seeking) were compared between diagnostic groups using the Toddler Sensory Profile-2. The cascading effect were examined through Structural Equation Modeling and temporally ordered path analysis to test direct and indirect effects of early sensory differences on subsequent autistic traits via the mediation of social skills in autism. Compared to typical development, infants later diagnosed with autism exhibited significantly elevated sensory sensitivity and sensory avoiding, along with elevated sensory registration scores at 12 months, with sensory sensitivity showing differential trajectories over time (F = 3.25, p = 0.004). Elevated sensory avoiding at 18 months exerted an indirect effect on social-communication at 36 months via the mediating role of social skills at 24 months (B = 0.08, p = 0.007). Additionally, temporally ordered path analysis revealed that elevated sensory avoiding at 18 months negatively predicted social skills at 24 months (β = -0.19, p = 0.030). Notably, in an exploratory analysis, increased sensory seeking at 18 months positively predicted adaptive skills at 36 months (B = 0.97, p = 0.031). Sensory differences emerge as early as 12 months in infants who later receive an autistic diagnosis, with sensory sensitivity demonstrating distinct developmental trajectories. These findings provide prospective evidence to support the cascading effect model in autism, identifying early sensory avoiding as an important early correlate of subsequent social-communicative development. Furthermore, early sensory seeking behaviors may facilitate subsequent adaptive functioning, highlighting the heterogeneous developmental pathways within autism. www.chictr.org.cn; Trial No: ChiCTR2100049811; Trial Date:2021.08.10.