Intellectual Disability – Types, Symptoms, Causes, Treatments And More.

The intellectual disabilities makes children with the condition may take longer than normal children sit, crawl, walk, talk and take care of personal needs, have trouble learning to pace with other children at school. Children with disabilities experience considerable challenges in two main areas: intellectual functioning and adaptive behavior.

Adaptive behavior involves the use of everyday life skills, researchers have discovered hundreds of causes of intellectual disability, but for about a third of affected people, the cause remains a mystery.

What is intellectual disability?

Also called developmental disability or mental retardation, it is a condition that begins in the developmental period of life and includes below-average general intellectual function and a lack of skills necessary for independent daily living.

It is a term used when a person has certain limitations in mental functioning and skills such as communication, self-care and social skills. These limitations will make a child learn and develop more slowly than a typical child. Children may take longer to learn to talk, walk and attend to their personal needs, such as dressing or eating, they are likely to have trouble learning in school. They will learn, but it will take longer, there may be some things that they cannot learn.

Once focused almost exclusively on cognition, the definition now includes both a component related to mental functioning and one related to the functional abilities of individuals in their environments. As a result of this focus on the skills of the person in practice.

Intellectual disability affects approximately 2-3% of the general population, 75% to 90% of affected people have it mildly. Non-syndromic or idiopathic cases account for 30-50% of cases and about a quarter of cases are caused by a genetic disorder, and approximately 5% are inherited from a person’s parents. Cases of unknown cause affect around 95 million people as of 2013.

People with an intellectual disability can process information more slowly than others, they have difficulties communicating and managing daily life skills, and they also have difficulties with abstract concepts such as money and time.

Three areas of adaptive functioning are considered:

Conceptual:  Language , reading, writing, mathematics, reasoning, knowledge, memory

Social:  Empathy, social judgment, communication skills, the ability to follow rules, and the ability to make and maintain friendships.

Practical:  Independence in areas such as personal care, job responsibilities, money management, recreation, and organization of school and work assignments

Adaptive functioning is assessed through standardized measures with the individual and interviews with others, such as family members, teachers, and caregivers.

Intellectual disability is identified as mild, moderate or severe, symptoms of intellectual disability begin during childhood or adolescence, delays in language or motor skills can be seen at two years. However, mild levels of intellectual disability may not be identified until school age when a child may struggle with academics.

Types of intellectual disability

According to DSM 5, there are mild, moderate, severe and profound classifications.

Mild (IQ 50-55 to 70)

85% of people with intellectual disabilities have a mild disability.

  • Conceptual domain:  Mildly affected abstract thinking , functional abilities, cognitive flexibility, and short-term memory.
  • Social domain:  Immature social interactions, which puts them at risk of manipulation.
  • Practical domain: Requires supervision, guidance and assistance to carry out the tasks of daily living. This help is very important particularly in stressful situations. Sometimes they do not seem to be any different from children without this disability until they grow up.

Moderate (IQ 35-40 to 50-55)

10% with the disorder have moderate disabilities.

  • Conceptual domain: Requires continuous assistance to complete daily activities, it is even necessary that other people assume some of their responsibilities. With moderate supervision, they can learn skills related to their own personal care, they can perform unskilled or semi-skilled jobs, but always with supervision.
  • Social domain: When communicating verbally, their language is less rich and complex than people without disabilities, this means that they cannot interpret certain social subtleties correctly and that they have problems establishing new relationships.
  • Practical Mastery: With ongoing support and instruction they can develop certain skills and abilities.

Severe (IQ 20-25 to 35-40)

3-4% of people with intellectual disabilities have a severe disability.

  • Conceptual mastery: Very limited, especially with numerical concepts, they need constant support in many areas.
  • Social domain: Their oral language is very elementary, their sentences are grammatically simple and they have a limited vocabulary. They communicate very simply and are limited to the present.
  • Practical Mastery: Requires constant supervision for all day-to-day tasks.

Profound (IQ 20-25)

Although they are a minority (1% -2%), the majority are related to an identified neurological disease.

  • Conceptual domain: Clearly impacted, they only think about the physical world and non-symbolic processes, with instruction, they can acquire certain skills such as pointing. The associated motor and sensory difficulties often impede the functional use of objects.
  • Social domain: Poor understanding of verbal and gestural communication, they are expressed in a very basic, simple and mostly non-verbal way.
  • Practical domain: They are totally dependent in all areas, only if they do not have motor or sensory impairments can they participate in certain basic activities.

Signs and symptoms of intellectual disability

It begins during childhood and involves deficiencies in mental and social skills and basic activities of daily life. There are often no physical signs of mild forms of identification, although there may be characteristic physical features when associated with a genetic disorder (eg, Down syndrome).

  • The level of impairment varies in severity for each person. Some of the early symptoms may include:
  • Delays in reaching or not reaching milestones in the development of motor skills (sitting, crawling, walking).
  • Slow learning to speak or ongoing difficulties with speech and language.
  • Difficulty with self-help and self-care skills (eg, dressing, washing, and feeding).
  • Little ability to plan or solve problems.
  • Behavior problems
  • Inability to grow intellectually.
  • Trouble staying in school.
  • Lack of adaptation or adjustment to new situations.
  • Difficulty understanding and following social rules.

What are the causes of intellectual disability?

Experts have identified three main causes, these include:

Mental health professionals and physicians classify these intellectual impairments and the causes of intellectual disability in the following ways:

Genetic conditions

Intellectual disabilities caused by genetics come from abnormal genes, parents can pass these abnormal genes to children or errors can arise when genes combine in the womb causing intellectual disability, abnormal genes can occur from infections during pregnancy or from overexposure to X-ray radiation. Intellectual disabilities associated with various genetic diseases, such as:


It is a genetic disorder caused by a missing or defective enzyme, children with it cannot process a protein known as phenylalanine. Without proper care and treatment, it builds up in the blood and causes intellectual disability.

Down syndrome

It is a chromosomal disorder, these types of disorders occur randomly, too many or too few chromosomes cause these conditions. Sometimes a change in structure can cause them.

Fragile X syndrome

It is a genetic disorder located on the X chromosome, it represents one of the main causes of intellectual disability.

Pregnancy problems

Pregnant mothers who use alcohol or drugs during pregnancy put their developing babies at risk for intellectual disability. In fact, one of the best ways to lower your risk is to completely avoid alcohol and smoking during pregnancy because it can increase your risk. Other risk factors during pregnancy include:

  • Malnutrition
  • Environmental toxins (i.e., mercury, lead).
  • Maternal infections: toxoplasmosis, cytomegalovirus, rubella.

Problems during birth

Premature birth and low birth weight represent risk factors and indicate more serious problems to come. Sometimes oxygen deprivation or other injuries occur during the birth process and subsequently cause intellectual disability.

Problems after birth

Sometimes childhood illnesses can damage the brain and cause characteristics of intellectual disability.

Cultural factors

Children living in poverty have a much higher risk of exposure to environmental toxins, disease and malnutrition, all of which increase the risk that they will develop characteristics of intellectual disability. In addition, people living in poverty may miss out on important cultural and educational experiences available to other children.

How is intellectual disability diagnosed?

Intellectual disabilities are diagnosed by looking at two main things. These are:

  • The ability of a person’s brain to learn, think, solve problems, and make sense of the world (known as IQ or intellectual functioning).
  • Whether the person has the skills they need to live independently (called adaptive behavior or adaptive functioning).

Intellectual functioning is generally measured with a test called IQ, the average score is 100. It is considered that people who obtain scores below 70 to 75 have an intellectual disability, to measure adaptive behavior, professionals observe what a child can do compared to other children his age.

Treatment for intellectual disability

As we have said before, it is a lifelong condition, but early and continuous intervention can improve functioning and allow the person to prosper throughout their life, it can also be influenced by underlying medical or genetic conditions and by co-occurring conditions.

Once the diagnosis is made, help for people with intellectual disabilities focuses on looking at the strengths and needs of the individual and the supports they need to function at home, at school / work, and in the community.

Another important point that I have emphasized throughout the article is the importance of providing adequate therapy and support to the person with intellectual disability, this implies that the therapies must be individualized and an evaluation will have to be carried out beforehand to satisfy the needs. needs of the person, keep in mind that not all people with disabilities are the same, do not need the same therapies or require the same intensity of those therapies in all areas and activities of their life.

Services for people with intellectual disabilities and their families provide support to enable full inclusion in the community. Many different types of supports and services can help, such as:

  • Early intervention (infants and young children).
  • Special education.
  • Family support (for example, respite care).
  • Transition services.
  • Vocational programs.
  • Day programs.

Supports can come from family, friends, co-workers, community members, or from a service system. Job training is one example of support that a service system can provide, with the right support, people with intellectual disabilities can play productive and successful roles in society.

A diagnosis determines eligibility for services and protection of rights, such as special education services and home and community services. The American Association on Intellectual and Developmental Disabilities emphasizes that the main reason for evaluating people with intellectual disabilities is to be able to identify and implement the supports and services that will help them thrive in the community throughout their lives.

Tips for Parents of Children with Intellectual Disabilities

As we all know, whether or not they have an intellectual disability, it is different, we are all different, each family is also different and each person treats situations and moments differently. However, parents play a primary and fundamental role in our life. Here are some helpful tips:

1. If you observe behaviors or reactions that are not expected in your child or if you have doubts about whether something is happening to him, seek professional help as soon as possible, this is a very important point as it dispels your doubts and also allows the intervention to occur as soon as possible.

2. Once the diagnosis of the disability is confirmed, negative feelings such as anger, guilt and sadness will be noted. This is perfectly understandable and normal, you will have to take time to process them and then take steps for their acceptance and recognition, you can do this with the help of other parents who have been through the same thing or with a professional.

3. A very important challenge will be to differentiate the things that we can change from those that we cannot, this allows us to spend our resources on things that we can change and not waste time on other irrelevant aspects.

4. Research all information about your child’s disability, whether intellectual or otherwise, and what it can do throughout his development. Stay informed about recent studies with scientific evidence and therapies, as well as through families experiencing the same disabilities.

5. Find out about therapies that might be helpful for your child and your family.

6. Value professional opinions as much as non-professional ones.

7. Share and enjoy with your child, keeping in mind that although he will go through the same developmental stages at a slower rate than other children, he can still enjoy every minute. Don’t underestimate him or treat him like a child.

Georgia Tarrant
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Hello, how are you? My name is Georgia Tarrant, and I am a clinical psychologist. In everyday life, professional obligations seem to predominate over our personal life. It's as if work takes up more and more of the time we'd love to devote to our love life, our family, or even a moment of leisure.