title: Behavioral, cognitive, and adaptive development in infants with autism spectrum disorder in the first 2 years of life.
abstract: BACKGROUND
  To delineate the early progression of autism spectrum disorder (ASD) symptoms, this study investigated developmental characteristics of infants at high familial risk for ASD (HR), and infants at low risk (LR).
  
  
  METHODS
  Participants included 210 HR and 98 LR infants across 4 sites with comparable behavioral data at age 6, 12, and 24 months assessed in the domains of cognitive development (Mullen Scales of Early Learning), adaptive skills (Vineland Adaptive Behavioral Scales), and early behavioral features of ASD (Autism Observation Scale for Infants). Participants evaluated according to the DSM-IV-TR criteria at 24 months and categorized as ASD-positive or ASD-negative were further stratified by empirically derived cutoff scores using the Autism Diagnostic Observation Schedule yielding four groups: HR-ASD-High, HR-ASD-Moderate (HR-ASD-Mod), HR-ASD-Negative (HR-Neg), and LR-ASD-Negative (LR-Neg).
  
  
  RESULTS
  The four groups demonstrated different developmental trajectories that became increasingly distinct from 6 to 24 months across all domains. At 6 months, the HR-ASD-High group demonstrated less advanced Gross Motor and Visual Reception skills compared with the LR-Neg group. By 12 months, the HR-ASD-High group demonstrated increased behavioral features of ASD and decreased cognitive and adaptive functioning compared to the HR-Neg and LR-Neg groups. By 24 months, both the HR-ASD-High and HR-ASD-Moderate groups demonstrated differences from the LR- and HR-Neg groups in all domains.
  
  
  CONCLUSIONS
  These findings reveal atypical sensorimotor development at 6 months of age which is associated with ASD at 24 months in the most severely affected group of infants. Sensorimotor differences precede the unfolding of cognitive and adaptive deficits and behavioral features of autism across the 6- to 24-month interval. The less severely affected group demonstrates later symptom onset, in the second year of life, with initial differences in the social-communication domain.
authors.affiliation: Department of Speech and Hearing Sciences, University of Washington, Seattle, WA USA.|Department of Psychology, University of Washington, Seattle, WA USA.
authors.forename: Annette
authors.initials: A
authors.lastname: Estes
authors.affiliation: Department of Pediatrics, University of Alberta, Edmonton, AB Canada.
authors.forename: Lonnie
authors.initials: L
authors.lastname: Zwaigenbaum
authors.affiliation: Department of Biostatistics, University of North Carolina, Chapel Hill, NC USA.|Carolina Institute for Developmental Disabilities, Chapel Hill, NC USA.
authors.forename: Hongbin
authors.initials: H
authors.lastname: Gu
authors.affiliation: Department of Speech and Hearing Sciences, University of Washington, Seattle, WA USA.
authors.forename: Tanya
authors.initials: T
authors.lastname: St John
authors.affiliation: The Center for Autism Research, Department of Pediatrics, Children's Hospital of Pennsylvania, University of Pennsylvania, Philadelphia, PA USA.
authors.forename: Sarah
authors.initials: S
authors.lastname: Paterson
authors.affiliation: Institute of Child Development, University of Minnesota, Minneapolis, MN USA.
authors.forename: Jed T
authors.initials: JT
authors.lastname: Elison
authors.affiliation: Carolina Institute for Developmental Disabilities, Chapel Hill, NC USA.|Department of Psychiatry, Duke University, Durham, NC USA.
authors.forename: Heather
authors.initials: H
authors.lastname: Hazlett
authors.affiliation: Department of Psychiatry, Washington University, St. Louis, MO USA.
authors.forename: Kelly
authors.initials: K
authors.lastname: Botteron
authors.affiliation: Department of Radiology, University of Washington, Seattle, WA USA.
authors.forename: Stephen R
authors.initials: SR
authors.lastname: Dager
authors.affiliation: The Center for Autism Research, Department of Pediatrics, Children's Hospital of Pennsylvania, University of Pennsylvania, Philadelphia, PA USA.
authors.forename: Robert T
authors.initials: RT
authors.lastname: Schultz
authors.affiliation: Montreal Neurological Institute, McGill University, Montreal, QB Canada.
authors.forename: Penelope
authors.initials: P
authors.lastname: Kostopoulos
authors.affiliation: Montreal Neurological Institute, McGill University, Montreal, QB Canada.
authors.forename: Alan
authors.initials: A
authors.lastname: Evans
authors.affiliation: Department of Psychiatry, Duke University, Durham, NC USA.|The Autism Speaks Foundation, New York, NY USA.
authors.forename: Geraldine
authors.initials: G
authors.lastname: Dawson
authors.affiliation: Department of Pediatrics, University of Alberta, Edmonton, AB Canada.
authors.forename: Jordana
authors.initials: J
authors.lastname: Eliason
authors.affiliation: Department of Speech and Hearing Sciences, University of Washington, Seattle, WA USA.
authors.forename: Shanna
authors.initials: S
authors.lastname: Alvarez
authors.affiliation: Carolina Institute for Developmental Disabilities, Chapel Hill, NC USA.|Department of Psychiatry, Duke University, Durham, NC USA.
authors.forename: Joseph
authors.initials: J
authors.lastname: Piven