title: Onset patterns in autism: correspondence between home video and parent report.
abstract: OBJECTIVE
  The onset of autism is usually conceptualized as occurring in one of two patterns, early onset or regressive. This study examined the number and shape of trajectories of symptom onset evident in coded home movies of children with autism and examined their correspondence with parent report of onset.
  
  
  METHODS
  Four social-communicative behaviors were coded from the home video of children with autism (n = 52) or typical development (n = 23). All home videos from 6 through 24 months of age were coded (3199 segments). Latent class modeling was used to characterize trajectories and determine the optimal number needed to describe the coded home video. These trajectories were then compared with parent reports of onset patterns, as defined by the Autism Diagnostic Interview-Revised.
  
  
  RESULTS
  A three-trajectory model best fit the data from the participants with autism. One trajectory displayed low levels of social-communication across time. A second trajectory displayed high levels of social-communication early in life, followed by a significant decrease over time. A third trajectory displayed initial levels of behavior that were similar to the typically developing group but little progress in social-communication with age. There was poor correspondence between home video-based trajectories and parent report of onset.
  
  
  CONCLUSIONS
  More than two onset categories may be needed to describe the ways in which symptoms emerge in children with autism. There is low agreement between parent report and home video, suggesting that methods for improving parent report of early development must be developed.
authors.affiliation: MIND Institute, University of California-Davis Health System, Sacramento, CA 95817, USA. sally.ozonoff@ucdmc.ucdavis.edu
authors.forename: Sally
authors.initials: S
authors.lastname: Ozonoff
authors.forename: Ana-Maria
authors.initials: AM
authors.lastname: Iosif
authors.forename: Gregory S
authors.initials: GS
authors.lastname: Young
authors.forename: Susan
authors.initials: S
authors.lastname: Hepburn
authors.forename: Meagan
authors.initials: M
authors.lastname: Thompson
authors.forename: Costanza
authors.initials: C
authors.lastname: Colombi
authors.forename: Ian C
authors.initials: IC
authors.lastname: Cook
authors.forename: Emily
authors.initials: E
authors.lastname: Werner
authors.forename: Stacy
authors.initials: S
authors.lastname: Goldring
authors.forename: Fottfam
authors.initials: F
authors.lastname: Baguio
authors.forename: Sally J
authors.initials: SJ
authors.lastname: Rogers
mesh_terms: D017668:Age of Onset; D001321:Autistic Disorder / Q000175:diagnosis* / Q000523:psychology; D001526:Behavioral Symptoms; D002140:California; D016022:Case-Control Studies; D002657:Child Development; D002675:Child, Preschool; D003120:Colorado; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D019370:Observation / Q000379:methods*; D010290:Parents; D012043:Regression, Psychology; D012919:Social Behavior; D014741:Video Recording