Developmental Trajectories of Effortful Control in Young Boys with Fragile X Syndrome

Marissa Mounts, University of South Carolina


Effortful control or the ability to suppress a dominant response to perform a subdominant response (Posner & Rothbart, 2000) is a temperament factor that develops during the first years of life in typically developing children and is related to positive social-emotional outcomes (Derryberry & Rothbart, 2007). Children with Fragile X Syndrome (FXS) show difficulties in modulating arousal and controlling attention suggesting impairment in effortful control (Cornish, Sudhalter, & Turk, 2004); however, effortful control has not been explicitly investigated in this population. Therefore, the primary aim of the current study is to better understand the developmental trajectories of effortful control in boys with FXS. Second, the study used a multidimensional approach to investigating this developmental trajectory by examining the role of adaptive behaviors and autistic symptoms in the development of effortful control in boys with FXS. Participants included 38 males with FXS assessed 3 to 4 times (121 observations) between the ages of 4 and 8. Results from this study did not find a specific developmental trajectory (i.e. increasing or decreasing across time) of effortful control across all observations and children; however, significant variability in effortful control trajectories across children was found. Variability in autistic symptom severity was also found to predict effortful control trajectories. Adaptive behaviors were not significant predictors. These results are important as they contribute to the understanding of the behavioral phenotype of FXS by showing individual differences exist and need to be taken into account for each child when developing and implementing treatment.