Intellectual Disability: What is it? Symptoms, Causes, Prevention, Diagnosis and Treatment

Also known as DI, and sometimes called mental retardation, it is characterized by an intelligence or mental capacity below average.

As well as a lack of skills necessary for daily life. There are different degrees of intellectual disability, from mild to profound.

What is intellectual disability?

An individual with intellectual disability has limitations in two areas. These areas are:

Intellectual functioning

Also known as CI, it refers to a person’s ability to learn, reason, make decisions and solve problems.

Adaptive behaviors

These are necessary skills for everyday life, such as being able to communicate effectively, interact with others and take care of yourself.

The IQ (intelligence coefficient) is measured by an IQ test. The average IQ is 100, with most people scoring between 85 and 115. A person is considered intellectually disabled if they have an IQ of less than 70 to 75.

To measure a child’s adaptive behaviors, a specialist observes the child’s abilities and makes a comparison with the skills of other children of the same age.

The things that can be observed include how well the child can feed or dress himself; how well the child can communicate and understand others; and how the child interacts with his family, friends and other children of the same age.

It is believed that intellectual disability affects approximately 1% of the population. Of those affected, 85% have mild intellectual disability. This means that they are a bit slower than the average to learn new information or skills. With the right support, most will be able to live independently as adults.

What are the signs or symptoms of intellectual disability in children?

There are many different signs of intellectual disability in children. The signs may appear during childhood, or may not be visible until the child reaches school age. It often depends on the severity of the disability. Some of the most common signs of intellectual disability are:

  • Turn, sit, crawl or walk late.
  • Speaking late or having trouble talking.
  • Slow to master things like toilet training.
  • Difficulty remembering things
  • Inability to connect actions with consequences.
  • Behavioral problems like explosive tantrums.
  • Difficulty with problem solving or logical thinking.

In children with severe or profound intellectual disability, there may also be other health problems. These problems can include seizures, mood disorders (anxiety, autism, etc.), impairment of motor skills, vision problems or hearing problems.

What causes intellectual disability?

Every time something interferes with the normal development of the brain, an intellectual disability can occur. However, a specific cause of intellectual disability can only be identified approximately one third of the time.

The most common causes of intellectual disability are:

Genetic conditions

These include things like Down syndrome and fragile X syndrome.

Problems during pregnancy

Things that can interfere with the brain development of the fetus include alcohol or drug use, malnutrition, certain infections or preeclampsia .

Problems during childbirth

Intellectual disability can occur if a baby is deprived of oxygen during delivery or is born extremely premature.

Illness or injury

Infections such as meningitis, whooping cough or measles can cause intellectual disability. Serious head injuries, near drowning, extreme malnutrition, infections in the brain, exposure to toxic substances such as lead and gross negligence or abuse can also cause it.

None of the above

In two-thirds of all children with intellectual disabilities, the cause is unknown.

Can intellectual disability be prevented?

Certain causes of intellectual disability are preventable. The most common of these is the fetal alcohol syndrome. Pregnant women should not drink alcohol.

Getting adequate prenatal care, taking a prenatal vitamin and getting vaccinated against certain infectious diseases can also reduce the risk of your child being born with intellectual disabilities.

In families with a history of genetic disorders, genetic testing can be recommended before conception.

Certain tests, such as ultrasound and amniocentesis, can also be done during pregnancy to look for problems associated with intellectual disability. Although these tests can identify problems before birth, they can not correct them.

How is intellectual disability diagnosed?

Intellectual disability can be suspected for many different reasons. If a baby has physical abnormalities that suggest a genetic or metabolic disorder, various tests can be performed to confirm the diagnosis.

These include blood tests, urinalysis, imaging tests to look for structural problems in the brain, or electroencephalograms (EEG) to look for evidence of seizures.

In children with developmental delays, the doctor will perform tests to rule out other problems, including hearing problems and certain neurological disorders. If another cause for delays can not be found, the child will be referred for a formal test.

There are three factors that influence the diagnosis of intellectual disability: interviews with parents, observation of the child and intelligence tests and adaptive behaviors.

It is considered that a child is intellectually disabled if he has deficits in the IQ and adaptive behaviors. If only one or the other is present, the child is not considered intellectually disabled.

After making a diagnosis of intellectual disability, a team of professionals will evaluate the child’s particular strengths and weaknesses. This helps them determine how much and what kind of support the child will need to succeed in the home, school and community.


For infants and toddlers, early intervention programs are available.

A team of professionals works with parents to write an Individualized Family Service Plan or PSFI. This document describes the specific needs of the child and what services will help the child thrive. Early intervention may include speech therapy, occupational therapy,

School-age children with intellectual disabilities (including preschoolers) are eligible to receive special education free of charge through the public school system. This is a mandate of the Individuals with Disabilities Education Act (LEID).

Parents and educators work together to create an Individualized Education Program (IEP), which describes the child’s needs and the services the child will receive at school.

The goal of special education is to make adaptations and modifications that allow a child with an intellectual disability to succeed in the classroom.

What can I do to help my child with intellectual disability?

Steps to help your child with intellectual disabilities include:

  • Learn everything you can about intellectual disability: the more you know, the better advocate you can be for your child.
  • Encourage your child’s independence: let your child try new things and encourage him to do things by himself. Provide guidance when necessary and make positive comments when your child does something right or masters something new.
  • Have your child participate in group activities: taking an art class or participating will help your child develop social skills.
  • Stay involved: By staying in touch with your child’s teachers, you can track their progress and reinforce what your child is learning at school through home practice.
  • Meet other parents of children with intellectual disabilities: they can be a great source of advice and emotional support.