title: Heterogeneity and plasticity in the development of language: a 17-year follow-up of children referred early for possible autism.
abstract: BACKGROUND
  Delayed, abnormal language is a common feature of autism and language therapy often a significant component of recommended treatment. However, as with other disorders with a language component, we know surprisingly little about the language trajectories and how varied these might be across different children. Thus, we know little about how and when language problems might resolve, whether there are periods of relative stability or lack of change and what periods might offer more favourable circumstances for intervention.
  
  
  METHODS
  Expressive and receptive language was measured on six occasions between age 2 and 19 on a cohort of 192 children initially referred for autism. Latent class growth models were fitted to characterize the patterns of heterogeneous development.
  
  
  RESULTS
  Latent class growth analysis identified seven classes. Between age 6 and 19, all classes tracked in parallel. Between ages 2 and 6, development was more heterogeneous with considerable variation in relative progress. In all groups, receptive and expressive language developed very largely in tandem.
  
  
  CONCLUSIONS
  The results confirmed previous analysis of children with specific language impairment where progress beyond age 6 was remarkably uniform. Greater variation was evident before this age with some groups making clearly better or worse progress compared to others. While this developmental heterogeneity may simply be a reflection of variation in preexisting and unchanging biological disposition, it may also reflect, at least in part, greater sensitivity in the early years to environments that are more or less supportive of language development. These findings contribute to the case for the importance of early intervention.
authors.affiliation: Department of Biostatistics, King's College London, Institute of Psychiatry, London, UK.
authors.forename: Andrew
authors.initials: A
authors.lastname: Pickles
authors.forename: Deborah K
authors.initials: DK
authors.lastname: Anderson
authors.forename: Catherine
authors.initials: C
authors.lastname: Lord
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D001321:Autistic Disorder / Q000150:complications / Q000175:diagnosis*; D002648:Child; D002675:Child, Preschool; D005500:Follow-Up Studies; D006801:Humans; D007804:Language Development; D007805:Language Development Disorders / Q000145:classification / Q000175:diagnosis* / Q000209:etiology; D009473:Neuronal Plasticity / Q000502:physiology*; D055815:Young Adult
keywords: Early intervention; heterogeneity; language impairment; plasticity