Intellectual disability begins in childhood. People with intellectual disability have limits in their mental functioning seen in below-average intelligence (IQ) tests and in their ability to communicate, socialize, and take care of their everyday needs. The degree of disability can vary from person to person. It can be categorized as mild, moderate, severe, or profound.
Several hundred causes of intellectual disability have been discovered, but many are still unknown. The most common ones are:
A child could be at higher risk for intellectual disability due to any of the causes listed above, or due to intellectual disability in other family members. If you are concerned that your child is at risk, tell your child's doctor.
Symptoms appear before a child reaches age 18. Symptoms vary depending on the degree of the intellectual disability. If you think your child has any of these symptoms, do not assume it is due to intellectual disability. These symptoms may be caused by other, less serious health conditions.
Learning and developing more slowly than other children of the same age
Difficulty communicating or socializing with others
Lower than average scores on IQ tests
Trouble learning in school
Inability to do everyday things like getting dressed or using the bathroom without help
Difficulty hearing, seeing, walking, or talking
Inability to think logically
The following categories are often used to describe the level of intellectual disability:
Slower than normal in all areas
No unusual physical signs
Can learn practical skills
Reading and math skills up to grades 3-6
Can conform socially
Can learn daily task skills
Functions in society
Noticeable delays, particularly speech
May have unusual physical signs
Can learn simple communication
Can learn elementary health and safety skills
Can participate in simple activities and self-care
Can perform supervised tasks
Can travel alone to familiar places
Significant delays in some areas; may walk late
Little or no communication skills, but some understanding of speech with some response
Can be taught daily routines and repetitive activities
May be trained in simple self-care
Needs direction and supervision socially
Significant delays in all areas
Congenital abnormalities present
Needs close supervision
Requires attendant care
May respond to regular physical and social activity
Not capable of self-care
If you suspect your child is not developing skills on time, tell the doctor as soon as possible. You will be asked about your child’s symptoms and medical history. A physical exam will be done. Standardized tests may be given that measure:
Intelligence—IQ tests measure a person’s ability to do things such as think abstractly, learn, and solve problems. A child may have intellectual disability if IQ test results are 70 or below.
Adaptive behavior—These are skills needed to function in everyday life, including:
Conceptual skills like reading and writing
Social skills like responsibility and self-esteem
Practical skills like the ability to eat, use the bathroom, and get dressed
Remove lead-based paint from your home. Have your child tested for lead levels in the blood.
Keep poisonous household products out of reach.
Aspirin is not recommended for children or teens with a current or
recent viral infection. This is because of the risk of
Reye syndrome, which can cause neurological problems. Ask your doctor which medications are safe for your child.
Causes and prevention of intellectual disabilities. The Arc website. Available at: http://www.thearc.org/page.aspx?pid=2453. Updated March 1, 2011. Accessed November 8, 2017.
Daily D, Ardinger H, et al. Identification and evaluation of mental retardation. Am Fam Physician. 2000;61(4):1059-1067.
Facts about intellectual disability. The Centers for Disease Control and Prevention website. Available at: http://www.cdc.gov/ncbddd/actearly/pdf/parents_pdfs/IntellectualDisability.pdf. Accessed November 8, 2017.
Questions and answers about persons with intellectual disabilities in the workplace. US Equal Employment Opportunities Commission website. Available at: http://www.eeoc.gov/laws/types/intellectual_disabilities.cfm. Accessed November 8, 2017.
Last reviewed November 2018 by
EBSCO Medical Review Board
Rimas Lukas, MD
Last Updated: 11/18/2015
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