Past research has demonstrated the ubiquitous presence and early emergence of sensory patterns, including hyperresponsiveness (HYPER), hyporesponsiveness (HYPO), and sensory interests, repetitions, and seeking behaviors (SIRS) in children with autism spectrum disorder (ASD), as well as the potential role of sensory processing as a key building block for higher-level social and cognitive functions. Whereas previous findings highlighted the cross-sectional differences of sensory patterns across age and diagnostic groups, it remains unclear how the developmental trajectories of sensory patterns in ASD differ from those with other diagnostic outcomes. More evidence is needed to understand the developmental and heterogeneous nature of sensory patterns in young children with ASD among a general population, as well as how they are associated with broader developmental outcomes, such as adaptive/maladaptive behaviors and participation, in order to evaluate the contribution of sensory patterns to the early identification, diagnosis and prognosis of children with ASD and/or other developmental challenges.
To address these empirical gaps, this dissertation aimed to 1) model developmental trajectories of sensory patterns from infancy to school age in a community sample and explore the demographic and clinical factors that may account for their variability; 2) identify developmental trajectory subtypes of sensory patterns as associated with school-age outcomes, and 3) understand the specific longitudinal impact of sensory patterns on school-age outcomes. We followed up on a longitudinal cohort of children (N=1,517) from a large community sample whose caregivers completed surveys regarding their child’s sensory patterns and other developmental concerns at three time-points: infancy (Time 1: 6-19 months), pre-school years (Time 2: 3-4 years), and school years (Time 3: 6-7 years). At Time 3, we collected additional outcome data on autism symptoms, adaptive/maladaptive behaviors, and activity participation in a subsample (N=389) that included families who had reported any diagnoses or concerns (N=312) and those who had not reported any diagnoses or concerns at previous time-points (N=77).
In Study 1, we conducted multivariate latent growth curve modeling (LGCM) with demographic covariates to estimate sensory trajectories from Time 1 to Time 3 with the full sample (N=1,517) and the results revealed highly variable longitudinal patterns across the three sensory patterns. Such variability could be partially explained by demographic characteristics (i.e., child’s sex, race, and parent education) and clinical outcome status (ASD and non-ASD conditions). Particularly, the slopes of HYPER and HYPO were better able to differentiate ASD from other conditions, including non-ASD children with sensory issues. Parent education accounted for more of the variations in trajectories of children’s sensory responsiveness than child’s sex and race. Furthermore, the latent growth factors of the three sensory patterns were associated with each other, indicating their co-occurrence and co-development over time. These findings from Study 1 support the potential utility of longitudinal sensory patterns from infancy for early detection of ASD and the pivotal role of family-tailored approaches to address young children’s sensory challenges.
To further address the variability that could not be explained by the known factors (i.e., demographics and clinical outcome status) in Study 1, we performed latent class growth analysis (LCGA) to identify the sensory trajectory subtypes from infancy to school age among the full sample in Study 2. We also examined how children classified to these trajectory subtypes differ in their demographic characteristics, clinical outcome status (ASD and non-ASD conditions), and school-age outcomes, including autism symptoms, adaptive/maladaptive behaviors, and activity participation. As a result, we identified five distinct subtypes that vary in latent growth factors across sensory patterns. Particularly, there was a subtype (3% of the sample) characterized by elevated and worsening sensory patterns and highly associated with ASD and poor school-age outcomes. The other four subtypes were characterized by low to moderate levels of sensory patterns and generally stable/improving trajectories and were associated with strengths and weaknesses in school-age outcomes. These results indicated that profiling children based on their early sensory trajectories may help to identify children who are more likely to experience developmental challenges at school age and may thus introduce opportunities for early intervention.
In Study 3, we examined the specific impacts of sensory trajectories on each school-age outcome variable. Multivariate LGCM was performed with demographic covariates and latent growth factor regressions, and school-age outcome variables were included in the model by being regressed onto the latent growth factor of sensory patterns. Overall, the change rate of HYPER was the most significant predictor of school-age outcomes. The initial levels of sensory patterns had indirect effects on some distal outcomes via the change rates of HYPER and HYPO. Differential impacts of HYPER and HYPO were observed on maladaptive behavior: HYPER was more associated with internalizing behavior while HYPO was more with externalizing behavior. Also, the variations in autism symptoms and maladaptive behavior were explained to larger extents by sensory trajectories as compared to other behavioral domains. These results indicate that early sensory challenges may have cascading effects on other domains of behavior. Thus, sensory responsiveness during this period may be an important target for early intervention towards more optimal outcomes.
Overall, the findings of these three studies enhance our understanding of the developmental and heterogeneous nature of sensory patterns from infancy to school age in a large community sample with various clinical characteristics, including ASD and non-ASD conditions. The observed associations between early sensory trajectories and later school-age outcomes may indicate the critical role of personalized intervention or services for children with sensory challenges and their families across early development towards optimal outcomes.