soft blurry rainbow background, square of green leaves and a young white woman with blonde hair holding a mug and looking off to the side - she has features associated with Down syndrome

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What is an Intellectual Disability (ID)?

A person with an intellectual disability (ID) has specific limitations in cognitive functioning and communication, social, or self-care skills.

These can cause a child to learn more slowly or differently than other children. ID can happen anytime before a child turns 18 years old, sometimes even before birth.  

Let’s talk a little more about what all that means.

What is the definition of ID?

According to the American Association of Intellectual and Developmental Disabilities (AAIDD), a person has ID when they meet the following criteria:

  1. An intelligence quotient (IQ) of 70-75 or below
  2. Significant limitations in two or more adaptive areas (life skills such as communication and self-care)
  3. A manifestation of the condition before age 18

Similarly, the Diagnostic and Statistical Manual of Mental Disorders of the American Psychiatric Association (APA) lists the criteria for ID as follows:

  1. Significant limitations in cognitive capacity (mental abilities)
  2. Significant limitations in adaptive functioning, including conceptual skills, social skills, and practical life skills 
  3. Appearance of the disability before age 18

Although the DSM-5 is known as the Diagnostic and Statistical Manual of Mental Disorders, intellectual disabilities are not disorders in and of themselves. Instead, ID can be caused by several things: genetic causes, brain injuries, and some types of medical conditions top the list. Because intellectual disabilities are not disorders, there are no treatments.

Here’s a good (short) video by the Special Olympics on what an intellectual disability actually is:

What are the causes of an Intellectual Disability?

ID can have several causes including complications during pregnancy, such as a maternal infection or toxic exposure; problems during birth, such as oxygen deprivation to the baby; or a childhood infection like measles, meningitis, or whooping cough. There are a lot of things, some genetic and some not, that can cause intellectual disability.

Examples include: 

Down Syndrome:

Down Syndrome  (Trisomy 21) is the most common genetic cause of ID. Down syndrome comes with about 1 out of every 800 births. During prenatal development, an extra chromosome develops on the 21st chromosome. (read more about Down syndrome here).

Fragile X Syndrome (FXS):

FXS is a genetic condition that occurs when a single gene on the X chromosome shuts down. This gene makes a protein needed for brain development. In FXS the protein is not made, and the brain does not develop typically. FXS can affect both sexes, with great variation among individuals. While many people with FXS have ID, many more have either normal IQ or learning disabilities. In addition to ID or learning disabilities, people with FXS may show signs of autism, attention deficit and hyperactivity (ADHD), anxiety and/or mood disorders, and epilepsy. 

Fetal Alcohol Spectrum Disorders (FASD) & Fetal Alcohol Syndrome (FAS):

FASD is an umbrella term for a variety of conditions children present with when they have been exposed to alcohol during their mothers’ pregnancies. Of these, the most common is FAS, which doctors diagnose in individuals who meet all of the following criteria:

  1. Small size for their age (below 10th percentile in weight or length)
  2. A smaller than average head (microcephaly)
  3. Certain facial features, like small, widely-spaced eyes and a smooth filtrum
  4. Mental and behavioral challenges, including ID

Other FASDs in which only some of the above symptoms may be present include Partial Fetal Alcohol Syndrome (pFAS), Alcohol-Related Neurodevelopmental Disorder (ARND), and Neurobehavioral Disorder associated with Prenatal Alcohol Exposure (ND-PAE.) FASDs may have symptoms that look like those of other conditions, including ADHD, autism, and behavioral health issues. However, all of these conditions are different.

What are the Characteristics or Signs of an Intellectual Disability?

The various causes of ID mean each person’s disability is unique. There is no specific set of traits or features people with ID share.

As noted above, certain conditions have specific associated physical and other characteristics that are typical of people with each condition, but the presence and degree of these characteristics vary from person to person. 

In addition to condition-specific signs, ID in general may be characterized by some or all of the following behavioral and/or psychological features:

Poor impulse control: People with ID often have trouble connecting cause and effect, which may cause problems with impulse control. For instance, suppose a child sees hot cookies coming out of the oven, and wants to grab one immediately, which will cause a nasty burn. Most children make this mistake only once or twice, learning quickly not to grab a cookie right out of the oven. For children with ID, learning to control such an impulse may take much longer.

Low frustration tolerance: When an impulse is inhibited, it requires the ability to tolerate a bit of frustration. Frustration tolerance is an important developmental skill which allows people to comfortably endure everyday frustrations. This in turn limits the unpleasant consequences of impulsive behavior. People with ID face increased opportunities for frustration because their abilities to solve problems and control their impulses are limited. When they experience frustration, some people with ID may respond in an impulsive, stubborn, and aggressive manner. Others may respond with passivity, withdrawal, and compliance. Low frustration tolerance may lead to self-harm. People with ID may exhibit some or all of these behaviors.

Low self-esteem: Self-esteem and self-confidence naturally develop as children learn to solve problems. However, limited mental capacity makes it difficult for a person to solve problems. Skillful problem solving requires sustained attention and persistence in the face of difficulty, which may be lacking in persons with ID. Thus they may develop low self-esteem. Psychiatric disorders related to low self-esteem, such as depression, may accompany ID. 

How Can We Find Out if Someone Has an Intellectual Disability?

Testing is available for a variety of conditions that cause ID. For example, simple, accurate, direct DNA testing for FXS was developed in 1992. It can detect both carriers of the Fragile X mutation, and affected individuals. Any doctor can order the FXS test, and most major U.S. medical centers offer it covered by health insurance. With conditions like Down Syndrome, prenatal testing can be done by chorionic villus sampling (CVS) or amniocentesis, although routine CVS or amniocentesis does not usually include FXS testing. Talk to your doctor or genetic counselor if you are interested in prenatal testing for FXS and other ID. 

Does Mental Retardation Always Come with Intellectual Disability?

“Intellectual disability” (ID) or “cognitive disability” has replaced “mental retardation” as the preferred term for this type of disability. Some aspects of ID are referred to as “developmental delays,” but this term can refer to physical or psychological as well as cognitive issues or impairments. Also, while there is some overlap between ID and developmental disability (DD), they are two distinct disability groups and should not be conflated. 

What is the “Mental Capacity” of Someone with an ID?

This is a tough one!

Most people with ID need some help in caring for themselves, as well as with things that involve  reasoning, planning, thinking, and judgment. This limited mental capacity makes it difficult to learn new things, including the skills needed for safe, socially responsible, independent living. Children with ID develop more slowly than other children, usually sitting, walking, and talking much later. This delayed development usually means they do not act their age.

However, as tempting as it may be to reduce an assessment of a person with ID to their “mental age,” doing so can be detrimental to that person’s self-concept and to perceptions of people with ID in general. It’s important to remember that, just as there is no specific set of characteristics people with ID share, each person’s disability, and the struggle they face because of it, is unique. One person with ID may have capacity in an area where another lacks it. While limited intelligence manifests itself in certain adaptive skill areas, not all people with ID lack all of the same skills and abilities. Mental capacity/intelligence varies among people with ID as among people in the general population. 

What services and supports are available to help people with ID lead rewarding and full lives?

Your state has programs to help out.

You need to find where to connect with a coordination specialist (or service coordinators), who works with your state’s ID programs. That person will help connect you with community services. Once connected, they will develop an Individual Support Plan (ISP), which is to provide the right mix of resources to really help. These supportive services may include:

  • social skills training
  • supported housing and/or employment
  • medical and dental care
  • occupational, physical, and speech  therapy
  • mental/behavioral health services
  • financial resources
  • family supports
  • legal and advocacy services
  • social, leisure, and recreational activities
  • adult daycare services
  • public transportation

Organizations like The Arc, the National Down Syndrome Congress, and the National Organization on Fetal Alcohol Syndrome (NOFAS) can help figure these pieces out.

You should definitely also google: your state + department of intellectual disability, or your state + intellectual disability 

Don’t stop there! Head over to Facebook, and connect with a group that relates to the particular intellectual disability that you are trying to find resources for: 100+ Disability Groups on Facebook You really want to ask from within specific disability groups to find people who have walked that path already and can offer you some ‘best practices’ in connecting with resources from within your state.

Listen to People with Intellectual Disabilities

“Nothing About Us Without Us,” is the call of the disability community, and Intellectual Disability is included in this. In striving to better understand ID and to be better allies, we need to tune in and LISTEN to people with intellectual disabilities. What do THEY say about having an intellectual disability? What do THEY say it’s all about?

This was an excellent TED Talk by Loretta Claiborne which I found on YouTube, but there are so many voices out there, asking to be heard. Let’s do that; let’s listen, and be the allies we want to be. 

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One Comment

  1. This is a great topic. Thank you for discussing this. So many people will understand intellectual disability, and people have it.

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