Return to Index
What Is an Intellectual Disability?
- IQ below 70
Significant limitations exist in two or more adaptive skill areas. These include:
- Community use
- Functional academics (reading, writing, basic math)
- Health and safety
- Home living
- Social skills
- The disability begins before age 18
What Are the Causes?
- Phenylketonuria (PKU) —Children born with this rare genetic disorder cannot metabolize phenylalanine (PHE), which is an amino acid found in food. Without proper treatment, PKU can lead to intellectual disability.
- Down syndrome —In a normal fertilized egg, chromosomes exist in pairs. But, in the case of Down syndrome, there are three of chromosome 21.
- Fragile X syndrome —This is caused by mutations of the FMR1 gene, the leading cause of inherited intellectual disability.
Problems During Pregnancy
- Certain environmental toxins (eg, lead)
- Illnesses of a mother during pregnancy that can be passed on to her infant, such as:
- Prescription medicines (eg, isotretinoin [Accutane], phenytoin [Dilantin])
Problems at Birth
Problems After Birth
How Is an Intellectual Disability Diagnosed?
- Conceptual skills—For example, can the person read and write? Does he understand concepts like time and money?
- Social skills—Does the person follow rules? Does he have interpersonal skills? Can he solve social problems?
- Practical skills—Can the person take care of his daily needs? Can he work, use money, and keep himself safe?
What Are the Treatment Options?
- Case management
- Special education
- Job training
- Housing services
- Transition services
- Family support (eg, respite care for caregivers)
- Early intervention
Can Intellectual Disabilities Be Prevented?
- Phenylketonuria (PKU)
- Congenital hypothyroidism
- Early and comprehensive prenatal care, including prenatal vitamins containing folate
- Abstaining from alcohol, tobacco, and drugs during pregnancy
American Association on Intellectual and Developmental Disabilities http://www.aaidd.org/
Developmental Disabilities Centers for Disease Control and Prevention http://www.cdc.gov/ncbddd/dd/default.htm/
Best Buddies http://www.bestbuddies.ca/
Live, Work, Play http://www.liveworkplay.ca/
Definition of intellectual disability. American Association on Intellectual and Developmental Disabilities website. Available at: http://www.aamr.org/content%5F100.cfm?navID=21. Accessed August 22, 2012.
Intellectual disability. The ARC website. Available at: http://www.thearc.org/page.aspx?pid=2543. Accessed August 22, 2012.
Children who are mentally retarded. The American Academy of Child and Adolescent Psychiatry website. Available at: http://www.aacap.org/cs/root/facts%5Ffor%5Ffamilies/children%5Fwho%5Fare%5Fmentally%5Fretarded. Published July 2004. Accessed August 22, 2012.
Diagnostic adaptive behavior scale. American Association on Intellectual and Developmental Disabilities website. Available at: http://www.aaidd.org/intellectualdisabilitybook/content%5F2687.cfm?navID=283 . Accessed August 22, 2012..
Intellectual disability. EBSCO Health Library website. Available at: http://www.ebscohost.com/healthLibrary/ . Updated June 2012. Accessed August 22, 2012.
Intellectual disability. Kronkosky Charitable Foundation website. Available at: http://www.kronkosky.org/research/Research%5FBriefs/Intellectual%20Disability%20May%202009.pdf . Published May 2009. Accessed August 22, 2012.
Intellectual disability. National Dissemination Center for Children With Disabilities website. Available at: http://nichcy.org/disability/specific/intellectual . Updated January 2011. Accessed August 22, 2012.
Intellectual disability. Merck website. Available at: http://www.merckmanuals.com/home/childrens%5Fhealth%5Fissues/learning%5Fand%5Fdevelopmental%5Fdisorders/intellectual%5Fdisability.html . Updated February 2009. Accessed August 22, 2012.
- Reviewer: Brian Randall, MD
- Review Date: 08/2012
- Update Date: 08/23/2012