The emergence and stability of attention deficit hyperactivity disorder in boys with fragile X syndrome

Abstract

Background Children with fragile X syndrome (FXS) are at high risk for developing a range of behavioral disorders, including Attention Deficit/Hyperactivity Disorder (ADHD) and autism spectrum disorders (ASD). However, very few studies have investigated the comorbid profile of FXS and ADHD and the possible dissociation from the FXS and ASD profile. The present study examined the relationship of childhood temperament characteristics of the Surgency facet (activity level, impulsivity, approach, shyness, and smiling and laughter) and the severity of ADHD and ASD features at two measurement time points in childhood, preschool (ages 3–4) and at school entry (ages 5–6). Methods The study consisted of males with FXS measured at each time point (preschool and school entry), as well as comparison of typically developing (TD) boys at the preschool measurement time point. Parent reported measures of temperament and behavioral symptoms were collected at each time point. Multiple regression analyses were used to analyze obtained data. Results Elevated activity level scores are associated with ADHD scores at preschool age and elevated shyness and decreased smiling and laughter is strongly associated with ADHD scores upon school entry. Impulsivity emerges as a strong indicator of elevated ADHD scores around school age, but even preschool impulsivity scores demonstrate some predictive value for higher ADHD scores later in school. Finally, no Surgency characteristic was significantly related to ASD scores at any age. Conclusions Impulsivity serves as an indicator of elevated ADHD symptoms across development periods in boys with FXS, while activity level is just indicative of higher ADHD scores at the preschool age. The Surgency facet of temperament at either age does not predict strong relationships of comorbid pathologies of ADHD and ASD in FXS. However, Surgency characteristics may serve as informative discriminative factors when studying behavioral outcomes in boys with FXS.

Boys with fragile X syndrome: investigating temperament in early childhood

“…Grefer et al . () concluded that boys with FXS demonstrate a unique developmental phenotype with respect to the etiology of attentional difficulties, as the same pattern of results was not observed for typically developing boys in this study.…”

“…impulsivity) conferring risk with respect to ADHD, and others, namely, smiling and laughter, buffering the risk for maladaptive behaviour (Grefer et al . ). Additional research is needed to clarify the role of the different facets of positive emotionality with respect to emerging symptoms of developmental psychopathology for children with FXS and other neurodevelopmental conditions.…”

“…; Grefer et al . ). The CBQ consists of 16 scales, contributing to three overarching temperament factors: negative affectivity (NA) – discomfort, sadness, fear, anger/frustration and soothability (negatively loading); surgency/extraversion (SE) – impulsivity, high intensity pleasure, activity level, approach, smiling/laughter and shyness (negatively loading); and effortful control (EC) – low intensity pleasure, inhibitory control, perceptual sensitivity, attentional focusing and attentional shifting.…”

“…; Grefer et al . ). Developmental changes in effortful control are likely especially consequential to this pattern of escalation, given that executive functions underlying effortful control develop rapidly between 3 and 7 years of age (Posner & Rothbart ), and children with FXS would be expected to lag behind, demonstrating less advanced attention‐based regulation.…”

“…In a longitudinal study conducted by Grefer et al . (), the contribution of surgency and its five fine‐grained component scales (i.e. activity level, approach, impulsivity, shyness and smiling/laughter) was examined in relation to the emergence and stability of attentional problems in 3‐ to 6‐year‐old boys with FXS.…”