Types of Intellectual Disability in Children and Coping

Intellectual disability (ID) is impaired development of learning, reasoning, social, and life skills. It often becomes apparent at birth or during childhood and continues through adulthood. This condition occurs in varying degrees and can result from genetic, environmental, or unknown factors.

For many decades, the medical establishment and the general public unkindly referred to affected individuals as “feeble-minded,” “moron,” “idiot,” and “imbecile.” During the 1960s, the American Association on Intellectual and Developmental Disabilities (AAIDD) and lawmakers adopted the term “mentally retarded,” which experts considered to be more sensitive at the time.

The term “intellectual disability” came about because of Rosa’s Law, passed in 2010 and named after a young girl with ID.

This article reviews ID, its causes, diagnosis, and related conditions. It also offers coping tips for parents.

What Does Intellectual Disability Mean?

Intellectual disability is “a disability characterized by significant limitations in both intellectual functioning and in adaptive behavior” (being able to cope in one’s environment).

When someone has an intellectual disability, they have limitations in their ability to learn, practice good judgment, and problem-solve (intellectual functioning); they may have difficulty communicating or be unable to live independently.

In some cases, individuals may not show signs of ID in early childhood but develop symptoms during adolescence or adulthood. 

Symptoms of Intellectual Disability in Children

Intellectual disability is the most common developmental disability. Approximately 439,000 affected children and youth ages 3 to 21 received support under the Individuals with Disabilities Education Act (IDEA) in 2019. However, the number of affected children could be higher because data were unavailable for some states.

Children with disabilities may experience issues with:

• Communication
• Socializing with their peers
• Taking care of their personal needs
• Developing more slowly than others their age
• Taking longer to walk, feed themselves, get dressed, and handle other daily functions

Some children may always require assistance with these activities.

Symptoms of Intellectual Disability in Adults

The life expectancy of adults with intellectual disabilities has increased over recent decades. For these people, aging comes with additional health risks compared to their peers because they are at higher risk of developing certain health conditions at an earlier age.

These health conditions include:

• Obesity
• Hyperlipidemia (high cholesterol)
• Diabetes
• Heart disease
• Hypertension (high blood pressure)
• Stroke
• Deep vein thrombosis
• Vision and hearing disorders

They also face discrimination and exclusion, which trigger secondary mental health disorders, such as anxiety and depression. Nevertheless, many adults with mild intellectual disabilities can thrive on their own or with minimal support.

Causes of Intellectual Disability

ID can be caused by a variety of factors, including injury, disease, or an issue with brain development. Chromosomal defects such as variants and inborn errors of metabolism can permanently alter cognitive function.

Intellectual disabilities arise from factors such as:

• Down syndrome, the most common cause of ID in the United States
• Fragile X syndrome, the most commonly known congenital (present at birth) cause of ID
• Fetal alcohol syndrome
• Dravet syndrome, a rare congenital cause of ID
• Huntington’s disease, a hereditary cause of late-onset ID
• Birth defects
• Infections before birth

Intellectual and developmental disabilities also stem from cognitive disruption due to:

• Brain malformations
• Prenatal exposure to alcohol, drugs, or other toxins such as lead or mercury
• Maternal infections or problems at birth leading to brain injury
• Pre- or postnatal brain infections

Diagnosing Intellectual Disability

Pediatricians and other child healthcare providers can screen for IDDs at your well-child visits and annual exams. You might complete a brief, standardized test that your pediatrician will score. A medical professional may interview you and observe your child for symptoms as well.

Gold-standard tests for intellectual disability include the Autism Diagnostic Observation Schedule (ADOS) and the Autism Diagnostic Interview, Revised.

In some cases, a chromosomal microarray analysis (CMA) or the array comparative genomic hybridization (aCGH) test is used to pinpoint genetic mutations. These tests are usually done by taking a small blood sample but sometimes saliva or skin tissue is also used for a CMA.

Evaluating Intellectual and Adaptive Functioning

Overall, intellectual disability is identified by problems in both intellectual and adaptive functioning, as such:

• Intellectual functioning: According to the American Psychiatric Association, intellectual functioning entails “reasoning, problem-solving, planning, abstract thinking, judgment, academic learning, and learning from experience.” 

• Adaptive functioning: This has to do with skills your child needs to live safely and responsibly. To evaluate functioning, clinicians assess behaviors via questionnaires or observations of the patient’s performance of a skill.

Evaluating Severity

The AAIDD uses the Supports Intensity Scale (SIS) to assess the severity of ID. It focuses on the types of supports an individual requires to thrive, not just the limitations of the mentally challenged, and ranks them as follows:

• Mild to moderate ID: Most individuals with ID have mild disabilities. They tend to be slower in cognition and daily living skills, but they can learn to function with minimal assistance. Those with moderate ID can travel to familiar places and use basic life skills with a little more help.
• Severe ID: Severe intellectual disability symptoms include major developmental delays and limited communication skills. Individuals may be able to care for themselves and learn simple daily routines. However, they need supervision in social settings and family or institutional care.
• Profound ID: People with profound ID typically have congenital syndromes. They cannot live on their own and require close attention and assistance with self-care. These individuals often have accompanying medical issues and physical limitations.

Related Conditions

Intellectual disability frequently co-occurs with other developmental, physical, medical, and psychiatric conditions. It can be challenging to identify these illnesses if the affected person has limited communication skills. Commonly related conditions include:

• Anxiety and depression disorders
• Autism spectrum disorder
• Cerebral palsy
• Defects of the heart, eyes, digestive tract, and other organs
• Epilepsy (neurological disorder affecting brain activity that causes seizures)
• Impulse control disorder

Other conditions associated with intellectual disability include:

Supporting People With Intellectual Disabilities

Both children and adults with intellectual disabilities need support.

Ways to support children with ID include the following:

• Encourage your child with mild to moderate ID to be responsible and independent.
• Give them chores and help them learn everyday self-care skills as they are able. Break down jobs into smaller steps telling them what to do, step-by-step, until the job is done.
• Give your child frequent feedback. Praise your child when he or she does well to help build their abilities.
• Read to your child and enjoy fun activities with them and your other family members.
• Find opportunities in your community for social activities (such as scouts, recreation center activities, sports, etc.) to help your child build social skills and have fun.

Your pediatrician and local school can be your partner in caring for your child with ID. Federal laws provide for special education and accommodations in public schools. You can ask for an evaluation to determine your child’s needs and help develop an Individualized Education Program (IEP) for a successful learning journey.

There are also ways to support adults with ID:

• Use clear, simplified language and try speaking slower, not louder (unless they have a hearing impairment)
• Treat them as you would your peers. Do not speak down to them. They love a good joke, tease, or challenge just like we do.
• Draw boundaries. Do not allow them to get away with bad behavior—just as you wouldn’t allow someone without intellectual disabilities to misbehave.
• Ask if you can help them before acting and assuming they need help.
• Consider appointing a “guardian” to make medical decisions through a legal document called a “durable power of attorney.”
• Provide support and help them develop skills with cooking, banking, transportation, social situations, health care visits, and jobs.