title: Heart activity and autistic behavior in infants and toddlers with fragile X syndrome.
abstract: The present study contrasted physiological arousal in infants and toddlers with fragile X syndrome to typically developing control participants and examined physiological predictors early in development to autism severity later in development in fragile X syndrome. Thirty-one males with fragile X syndrome (ages 8-40 months) and 25 age-matched control participants were included. The group with fragile X syndrome showed shorter interbeat intervals (IBIs), lower vagal tone (VT), and less modulation of IBI. Data suggested a nonlinear effect with IBI and autistic behavior; however, a linear effect with VT and autistic behavior emerged. These findings suggest that atypical physiological arousal emerges within the first year and predicts severity of autistic behavior in fragile X syndrome. These relationships are complex and dynamic, likely reflecting endogenous factors assumed to reflect atypical brain function secondary to reduced fragile X mental retardation protein. This research has important implications for the early identification and treatment of autistic behaviors in young children with fragile X syndrome.
authors.affiliation: University of South Carolina.
authors.forename: Jane E
authors.initials: JE
authors.lastname: Roberts
authors.forename: Bridgette
authors.initials: B
authors.lastname: Tonnsen
authors.forename: Ashley
authors.initials: A
authors.lastname: Robinson
authors.forename: Svetlana V
authors.initials: SV
authors.lastname: Shinkareva
mesh_terms: D001321:Autistic Disorder / Q000209:etiology / Q000503:physiopathology*; D002657:Child Development / Q000502:physiology; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005600:Fragile X Syndrome / Q000150:complications / Q000503:physiopathology*; D006321:Heart / Q000294:innervation / Q000502:physiology*; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D007223:Infant; D018730:Infant Behavior / Q000502:physiology; D008297:Male; D012720:Severity of Illness Index; D014630:Vagus Nerve / Q000502:physiology*