A prospective longitudinal study of infant anxiety and sensory responsivity as early markers for infants with typical and elevated likelihood of autism and ADHD

Abstract

This thesis explores the developmental pathways and consequences of differences in sensory responsivity and anxiety in early infancy. Alterations in different domains of sensory responsivity and anxiety may have differential developmental consequences. Identifying which early markers relate to later manifestations of autism and attention deficit hyperactivity disorder (ADHD) is important for understanding causal paths to symptom development. Since both of these conditions are highly heritable, tracking infants who have an older sibling with the condition, and thus are at an elevated likelihood (EL) of autism and ADHD themselves, from early in development, provides an essential insight into key developmental trajectories. The current study uses two cohorts of prospective longitudinal infant-siblings, who were followed from early infancy to toddlerhood, with parent-report assessments of sensory responsivity, anxiety and emerging autistic and ADHD traits at 10, 14, 24 and 36 months. The first cohort of the British Autism Study of Infant Siblings (BASIS) included infants with and without a family history of autism (N = 247; EL-autism N = 170 and Typical Likelihood (TL) N = 77). The second cohort consisted of children who took part in the Studying Autism and ADHD Risks (STAARS) study, which included EL-ADHD infants (N = 161; EL-autism N=80; EL-ADHD N=31; EL-autism/ADHD N=21 and TL N=29). Chapters 3 and 4 apply cross-lag panel modelling to these longitudinal datasets, with results suggesting 1) alterations in sensory responsivity are associated with later autistic traits, 2) taking into account different domains of sensory responsivity is key to understand specificity of effects, and 3) paths between anxiety and sensory responsivity did not replicate between cohorts. In Chapter 5, trajectory modelling indicated that sensory domains that associated with likelihood status (i.e., having an older autistic/ADHD sibling or not) were not the same as those associated with outcome traits. Alterations in early sensory responsivity are not unique to autism but also observed in ADHD. Taken together, this thesis indicates that further work is needed to probe into construct overlap and account for the inter-dependence of different aspects of sensory responsivities in the same analytical model. It also highlights the importance of replication studies and the need for careful sample ascertainment. Given the developmental nature of these constructs, this thesis underscores the importance of subsequent investigations extending into mid-childhood.

Date of Award	1 May 2024
Original language	English
Awarding Institution	King's College London
Supervisor	Tony Charman (Supervisor), Emily Jones (Supervisor) & Virginia Carter Leno (Supervisor)