title: Longitudinal patterns of repetitive behavior in toddlers with autism.
abstract: BACKGROUND
  Recent evidence suggests that restricted and repetitive behaviors may differentiate children who develop autism spectrum disorder (ASD) by late infancy. How these core symptoms manifest early in life, particularly among infants at high risk for the disorder, is not well characterized.
  
  
  METHODS
  Prospective, longitudinal parent-report data (Repetitive Behavior Scales-Revised) were collected for 190 high-risk toddlers and 60 low-risk controls from 12 to 24 months of age. Forty-one high-risk children were classified with ASD at age 2. Profiles of repetitive behavior were compared between groups using generalized estimating equations.
  
  
  RESULTS
  Longitudinal profiles for children diagnosed with ASD differed significantly from high- and low-risk children without the disorder on all measures of repetitive behavior. High-risk toddlers without ASD were intermediate to low risk and ASD positive counterparts. Toddlers with ASD showed significantly higher rates of repetitive behavior across subtypes at the 12-month time point. Repetitive behaviors were significantly correlated with adaptive behavior and socialization scores among children with ASD at 24 months of age, but were largely unrelated to measures of general cognitive ability.
  
  
  CONCLUSIONS
  These findings suggest that as early as 12 months of age, a broad range of repetitive behaviors are highly elevated in children who go on to develop ASD. While some degree of repetitive behavior is elemental to typical early development, the extent of these behaviors among children who develop ASD appears highly atypical.
authors.affiliation: Carolina Institute for Developmental Disabilities, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
authors.forename: Jason J
authors.initials: JJ
authors.lastname: Wolff
authors.forename: Kelly N
authors.initials: KN
authors.lastname: Botteron
authors.forename: Stephen R
authors.initials: SR
authors.lastname: Dager
authors.forename: Jed T
authors.initials: JT
authors.lastname: Elison
authors.forename: Annette M
authors.initials: AM
authors.lastname: Estes
authors.forename: Hongbin
authors.initials: H
authors.lastname: Gu
authors.forename: Heather C
authors.initials: HC
authors.lastname: Hazlett
authors.forename: Juhi
authors.initials: J
authors.lastname: Pandey
authors.forename: Sarah J
authors.initials: SJ
authors.lastname: Paterson
authors.forename: Robert T
authors.initials: RT
authors.lastname: Schultz
authors.forename: Lonnie
authors.initials: L
authors.lastname: Zwaigenbaum
authors.forename: Joseph
authors.initials: J
authors.lastname: Piven
mesh_terms: D000367:Age Factors; D001321:Autistic Disorder / Q000523:psychology*; D016022:Case-Control Studies; D002657:Child Development; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007223:Infant; D008137:Longitudinal Studies; D008297:Male; D013239:Stereotyped Behavior
keywords: Autism; high-risk siblings; repetitive behavior