Intergenerational associations in inhibitory control in FMR1 families

Inhibitory control (IC), the capacity to resist or suppress a dominant or automatic response, is a central component of self-regulation and executive functioning. Greater IC capacity in early development is also associated with a number of positive downstream outcomes. IC is highly heritable and susceptible to environmental influence in early development, highlighting a critical role of the family in transmitting and fostering this ability. Children with fragile X syndrome (FXS), an inherited neurodevelopmental disorder, and their mothers with the FMR1 premutation (FXp) both evidence heightened vulnerability for IC deficits, warranting a need for a better understanding of familial IC associations in FMR1 families. Informed by family systems and evocative gene by environmental interaction frameworks, the present cross-sectional, phenotypic study examined mother-child IC associations in early development in children with FXS and their FXp mothers in comparison to neurotypical (NT) mother-child dyads. We hypothesized that the association between maternal IC and child IC would be stronger for FMR1 families given the compounding genetic and environmental vulnerability for lower IC demonstrated in extant research. Consistent with prior research, the present study documented IC deficits in children with FXS as well as nuanced processing differences FXp mothers compared to controls. Intergenerational IC associations were found for NT families. In contrast to our hypothesis, no associations were found between measures of maternal IC and child IC in FMR1 families. Despite null findings for FMR1 families, family-based interventions targeting IC deficits in these mothers and children could result in positive outcomes for the entire family system.