title: The trajectory of psychiatric disorders in young people with intellectual disabilities.
abstract: OBJECTIVE
  This study addresses the question of how prevalence and patterns of psychiatric disorder change from childhood to adolescence in young people with intellectual disability (ID).
  
  
  METHODS
  A representative epidemiological sample of 582 young people with ID aged 4-19 years was surveyed in 1991-1992 and again in 1995-1996. The main measure of psychiatric disturbance was the developmental behaviour checklist (DBC), a 96 item parent/carer completed questionnaire with robust psychometric properties which provided an overall score, 6 subscale or syndrome measures of psychiatric disturbance and determined caseness.
  
  
  RESULTS
  The findings confirmed that about 40% of young people with ID had psychiatric disorders which persisted over 4 years. Clinically significant change in symptoms with either deterioration or improvement occurred in around 14% of the sample.
  
  
  CONCLUSIONS
  Psychiatric disorder is 3-4 times more prevalent in young people with ID than in the general population. Less than 10% of these young people receive specialist services for a problem which is numerically as large as schizophrenia.
authors.affiliation: Centre for Developmental Psychiatry, Clayton, Victoria, Australia. bruce.tonge@med.monash.edu.au
authors.forename: B
authors.initials: B
authors.lastname: Tonge
authors.forename: S
authors.initials: S
authors.lastname: Einfeld
mesh_terms: D000293:Adolescent; D001315:Australia / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D015897:Comorbidity; D003430:Cross-Sectional Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008607:Intellectual Disability / Q000453:epidemiology*; D008297:Male; D001523:Mental Disorders / Q000175:diagnosis / Q000453:epidemiology*