Biobehavioral Indicators of Social Fear in Young Children With Fragile X Syndrome

Abstract

Anxiety is among the most impairing conditions associated with Fragile X syndrome (FXS) and is putatively linked to atypical physiological arousal. However, few studies have examined this association in young children with FXS. The authors examined whether patterns of arousal and behavior during an experimental stranger approach paradigm differ between a cross-sectional sample of 21 young children with FXS and 19 controls (12–58 months old). Groups did not differ in mean levels of behavioral fear. Unlike the control group, however, the FXS group demonstrated increased facial fear at older ages, as well as age-dependent changes in associations between heart activity and distress vocalizations. These findings may inform theoretical models of anxiety etiology in FXS and early detection efforts.

Behavioral Markers of Emergent Stranger Anxiety in Infants and Toddlers with Fragile X Syndrome

“…Finally, building on the multiple methods we employed in this study, future studies may consider integrating psychophysiological measures to further inform individual differences in behavioral inhibition in FXS. This work is particularly relevant given previous studies documenting atypical autonomic profiles in infants and toddlers with FXS (Roberts et al, 2012; Tonnsen, Shinkareva, et al, 2013). …”

“…According to Porges’ polyvagal theory (Porges, 1995), the vagus has also evolved in humans to modulate social functioning by facilitating rapid responses to changing environmental demands, as well as by moderating muscles responsible for expressing emotion via facial expression and vocal intonation. Indeed, infants with FXS exhibit reduced RSA during a variety of tasks, including the stranger approach paradigm (Tonnsen et al 2013), contributing to theories that atypical vagal functioning may contribute to abnormal social behaviors observed in ASD and FXS (Klusek et al, 2015; Roberts, Tonnsen, Robinson, & Shinkareva, 2012; Tonnsen, Shinkareva, et al, 2013). …”

“…This task has been used to study stranger fear in children with FXS and in typically developing infants and children of similar developmental age to children in our sample (Brooker et al, 2013; Tonnsen, Shinkareva, et al, 2013). The Stranger Approach paradigm is divided into discrete stages that include baseline state of the child (30 s), the stranger knock (30 s), stranger kneel (120 s), and recovery state of the child (30 s).…”

“…The present study focused on coding three infant behaviors solicited across the stranger paradigm: facial fear, distress vocalizations, and escape behaviors. Behavioral data were coded by trained research assistants using parameters defined in previous studies (Izard, 1979; Scherr et al, 2017; Tonnsen, Shinkareva, et al, 2013), with interrater reliability maintained at K ≥ .80 (facial fear = .81, distress vocalizations = .82, escape behaviors = .80). The primary dependent variables were weighted average intensity of facial fear, distress vocalizations, and escape behaviors (Gagne, Van Hulle, Aksan, Essex, & Goldsmith, 2011).…”

“…Similarly, children with FXS display reduced eye contact and less approaching behavioral movements and facial expressions when introduced to a novel examiner (Roberts et al, 2007, 2009; Scherr, Hogan, Hatton & Roberts, 2017), with persistent eye gaze avoidance among children with FXS and co-occurring features of autism (Hall et al, 2009; Roberts et al, 2007; Scherr et al, 2017), similar to children with idiopathic ASD (Scherr et al, 2017). Atypical social approach behaviors also emerge early in development in FXS, with increased facial fear toward strangers observed in a cross-sectional sample of 12–58 month old children with FXS relative to non-FXS controls (Tonnsen, Shinkareva, Deal, Hatton, & Roberts, 2013). Thus, behavioral inhibition and social fear are common and early-emerging features of FXS, although the specific association between stranger fear and clinical outcomes in this population remain unclear.…”