Date of Award

2025

Document Type

Open Access Dissertation

Department

Psychology

First Advisor

Jane Roberts

Abstract

Self-regulation is a multifaceted construct that occurs on biological, cognitive, emotional, and behavioral levels. Self-regulatory abilities typically emerge in the first years of life and continuously develop through early adulthood. There is considerable interindividual variability in developmental trajectories of self-regulation which are associated with numerous adaptive and maladaptive outcomes. Factors influencing the development of self-regulation include interacting genetic and social environmental factors. Given the high heritability of self-regulation, within-family associations are common.

Individuals with Fragile X syndrome (FXS), an inherited, single-gene neurodevelopmental disorder, have heightened vulnerability for self-regulation deficits that are evident in early infancy; however, the developmental trajectories and underpinnings of self-regulation are poorly understood in this population. Additionally, despite evidence of impaired inhibitory control (IC) in women with the FMR1 premutation (FXp), many of whom are mothers of children with FXS, there has been little exploration of shared genetic risk for self-regulation deficits in these family systems. This dissertation study includes a two-part examination of self-regulation in children with FXS, including biobehavioral underpinnings, familial predictors, and outcomes.

We leveraged a biobehavioral, longitudinal approach to understanding the associations amongst different facets (i.e., cognitive, behavioral, physiological) of self-regulation in early childhood and their prediction of executive functioning in middle childhood in FXS (Chapter 1). Similar to extant research, we failed to find significant associations among the different facets and measures of self-regulation in both FXS and neurotypical children. Considering all facets of self-regulation, longitudinal analyses yielded physiological reactivity as the strongest early marker of executive dysfunction in middle childhood for children with FXS. Measuring and monitoring such physiological markers early in life may facilitate earlier intervention and identify children who are most vulnerable to potential executive dysfunction later in life.

In light of evidence of deficits in self-regulation across FMR1-related conditions (i.e., FXS, FXp), no study to date has looked at intergenerational associations. Informed by family systems and evocative gene x environmental interaction frameworks, we examined mother-child IC associations in FMR1 families compared to neurotypical families (Chapter 2). The present study replicated findings of IC deficits in children with FXS and FXp mothers. Whereas clear mother-child IC associations were found for neurotypical families, we failed to determine any relationships between measures of mother and child IC in FMR1 families. Measurement considerations are discussed. Altogether, findings suggest the intergenerational transmission of IC in FMR1 families deviates from neurotypical families, and likely highlights the role of intervening processes such as parenting or parent-child interaction quality in explaining group differences.

The aforementioned studies are both individually and collectively important for characterizing early self-regulation, including identifying salient markers and mechanisms of risk, in FXS. This knowledge is critical for determining who is most vulnerable to self-regulation deficits and ensuring targeted intervention; findings may also generalize to other neurodevelopmental disorders. Capitalizing on the malleability of the brain in early childhood, optimization of early biobehavioral self-regulatory processes may redirect developmental trajectories and promote long-term adaptive outcomes for children with FXS and their families.

Rights

© 2025, Erin Evelyn Hunt

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