Comorbidity of intellectual disability and mental disorder in children and adolescents: a systematic review

J Intellect Dev Disabil. 2011 Jun;36(2):137-43. doi: 10.1080/13668250.2011.572548.


Background: Mental disorder and intellectual disability each accounts for substantial burden of disease. However, the extent of this co-occurrence varies substantially between reports. We sought to determine whether studies in children and/or adolescents with acceptably rigorous methods can be distinguished from existing reports, and whether key risk factors could be ascertained.

Method: Published studies investigating the prevalence of mental disorders in children and/or adolescents with intellectual disability were reviewed.

Results: Nine studies with acceptable methods were identified, 4 which compared the prevalence of mental disorder in populations of those with and without intellectual disability, and a further 5 studies that estimated the rates of mental disorder in those with intellectual disability were identified. Collectively, these studies demonstrate rates of comorbidity for children and adolescents between 30 and 50% with a relative risk of mental disorder associated with intellectual disability ranging from 2.8-4.5. The risks for this comorbidity associated with age, gender, severity of intellectual disability, and socioeconomic status remain uncertain.

Conclusions: Appreciation of this comorbidity needs to be a fundamental component of both mental health and intellectual disability services.

Publication types

  • Review
  • Systematic Review

MeSH terms

  • Adolescent
  • Age Distribution
  • Child
  • Comorbidity
  • Humans
  • Intellectual Disability / epidemiology*
  • Intellectual Disability / psychology
  • Mental Disorders / epidemiology*
  • Prevalence
  • Risk
  • Risk Factors
  • Severity of Illness Index
  • Sex Factors
  • Social Class