Intellectual Disability: Levels, Causes, Symptoms and Treatment

Intellectual Disability


If your kid has an intellectual disability (ID), their brain hasn’t grown correctly or has been damaged in some way. Their brain may also not operate within the usual range of both intellectual and adaptive functioning. This disease was formerly known as “mental retardation” by medical experts.

There are 4 levels of ID:

  • Mild
  • Moderate
  • Severe
  • Profound

Sometimes, ID may be categorized as:

  • “Other”
  • “Unspecified”

ID includes both a low IQ and difficulties adapting to daily life. There may also be learning, speech, social and physical impairments.

Extreme cases of ID may be identified shortly after birth. However, you may not know your kid has a milder type of ID until they fail to achieve typical developmental objectives. Almost majority of cases of ID are detected before a kid reaches the age of 18.

Read: Conduct Disorder

Levels of intellectual disability

ID is split into four categories, depending on your child’s IQ and degree of social adjustment.

Mild intellectual disability

Some of the signs of mild intellectual disability usually involve:

  • Taking longer to learn to speak, yet communicating effectively once they know-how
  • Becoming completely independent in self-care as they grow older
  • Having difficulties with reading and writing
  • Social immaturity
  • Greater difficulty with the duties of marriage or parenthood
  • Benefitting from specialized schooling programs
  • IQ range of 50 to 69

Moderate intellectual disability

If your kid has a moderate ID, they may show some of the following


  • Are slow in learning and using language
  • May have some problems with communicating
  • Can acquire basic reading, writing and counting abilities
  • Are usually unable to live alone
  • Can frequently move about on their own to familiar areas
  • May take part in different kinds of social activities
  • IQ range of 35 to 49

Read: Conversion Disorder

Severe intellectual disability

Symptoms of severe ID include:

  • Significant motor impairment
  • Central nervous system has been severely damaged or developed abnormally.
  • IQ range of 20 to 34

Profound intellectual disability

Symptoms of profound ID include:

  • Incapacity to understand or comply with requests or directions
  • Potential immobility
  • Incontinence
  • Extremely basic nonverbal communication
  • Incapacity to care for their own needs freely
  • The necessity of continuous assistance and monitoring
  • IQ of less than 20

Read: Global Developmental Delay


People in this group are frequently physically handicapped, have hearing loss, are nonverbal or have a physical impairment. These circumstances may prohibit your child’s doctor from performing screening tests.


If your kid has an undefined ID, they will display symptoms of ID, but their specialist doesn’t have enough data to assess their degree of impairment.

Symptoms of intellectual disability

Intellectual disability symptoms will vary depending on your child’s level of disability that may include:

  • Inability to achieve intellectual milestones
  • Crawling, sitting or walking later than typical youngsters
  • Difficulties learning to talk or trouble to speak effectively
  • Memory difficulties
  • Failure to understand the effects of actions
  • Incapacity to think rationally
  • Childlike behavior inappropriate with the child’s age
  • Lack of curiosity
  • Learning challenges
  • IQ below 70

incapacity to live a fully independent life as a result of difficulties communicating, taking care of oneself or connecting with others

If your kid has an ID, they may suffer any of the following behavioral issues:

  • Aggression
  • Dependency
  • Disengagement from social activities
  • Attention-seeking conduct
  • Depression throughout teenage and teen years
  • Lack of self-control
  • Passivity
  • Propensity toward self-injury
  • Stubbornness
  • Low self-esteem
  • Little tolerance for frustration
  • Psychotic disorders
  • Trouble focusing attention

Some individuals with ID may also have unique physical features. These may include having a low height or facial abnormalities.

Read: Intellectual Development Disorder

What causes intellectual disability?

Doctors can’t always pinpoint a particular cause of ID. However, causes of intellectual disability may include:

  • Trauma before birth, such as an illness or exposure to alcohol, drugs or other poisons
  • Trauma during birth, such as oxygen deprivation or preterm delivery
  • Hereditary diseases, such as phenylketonuria (PKU) or Tay-Sachs disease
  • Chromosome problems, such as Down syndrome
  • Lead or mercury poisoning
  • Serious malnutrition or other nutritional problems
  • Extreme cases of early childhood disease, such as whooping cough, measles or meningitis
  • Brain damage

How is intellectual impairment diagnosed?

Your kid should have below-average intellectual and adaptive abilities to be diagnosed with ID. Your child’s doctor will conduct a three-part assessment that includes:

  • Interviews with you
  • Observations of your kid
  • Standard tests

Your kid will be given conventional IQ tests, such as the Stanford-Binet Intelligence Test. This will assist the doctor to assess your child’s IQ.

The doctor may also conduct additional tests such as the Vineland Adaptive Behavior Scales. This exam offers an evaluation of your kid’s everyday living skills and interpersonal skills abilities, compared to those children in the same age range.

It’s essential to note that children from various cultures and socioeconomic statuses may behave differently on these exams. To establish a diagnosis, the doctor will examine the test findings, conversations with you and observations of your child.

Your child’s assessment procedure may involve visits to experts, who may include a:

  • Psychologist
  • Speech pathologist
  • Social worker
  • Pediatric neurologist
  • Developmental pediatrician
  • Physical therapist

Laboratory and imaging testing may also be conducted. These may help a doctor to identify metabolic and genetic abnormalities, as well as structural concerns with your child’s brain.

Other diseases, including hearing loss, cognitive difficulties, neurological illnesses and emotional problems may also cause delayed growth. Your kid’s doctor should rule these diseases out before diagnosing your child with ID.

You, your kid’s school, and your doctor will combine the findings of these tests and assessments to create a treatment and education plan for your kid.

Read: Communication Disorders

Intellectual disability treatment

Your kid will probably require continuous therapy to help them deal with their disability.

You will receive a family service plan that outlines your child’s requirements. The plan will also describe the assistance that your kid will require to support them with normal growth. Your family requirements will also be considered in the strategy.

When your kid is ready to enter school, an Individualized Education Program (IEP) will be put in place to assist them with their educational requirements. Special education benefits all children with disabilities.

The federal Individuals with Disabilities Act (IDEA) mandates that public schools offer free and proper education for all children with ID and other developmental disabilities.

The primary aim of therapy is to assist your kid to achieve their maximum potential in terms of:

  • Education
  • Social skills
  • Life skills

Treatment may include:

  • Behavior therapy
  • Occupational therapy
  • Counseling
  • Medicine, in certain cases

Read: How to Know If You Have ADHD

Tips for Parents

  • Get help for your child, learn about his or her disability.
  • Parenting a child with a disability can be challenging.
  • Be patient; your child may need more time to learn.
  • Make sure your children are independent and responsible.
  • Know what your child deserves in terms of educational services.
  • Find out what laws help your child live a happy, healthy, and fulfilling life.
  • Seek out community sports, social, and recreational activities (such as Best Buddies).

Is it possible to prevent intellectual disability?

There are some causes of intellectual disability that can be prevented. One of the most common causes of these problems is fetal alcohol syndrome. Drinking alcohol during pregnancy is not recommended for pregnant women. Your baby’s risk of being born with intellectual disabilities can also be reduced by obtaining proper prenatal care, taking prenatal vitamins, and getting vaccinated against certain infectious diseases.

The recommendation of genetic testing before conception may be made in families with a history of genetic disorders.

It is also possible to perform certain tests during pregnancy to check for problems associated with intellectual disability, such as ultrasound and amniocentesis. However, these tests cannot correct problems that might be identified before birth.

Co-occurring and related disorders

It is common for individuals with intellectual disabilities to co-occur with mental health, neurodevelopmental, medical and physical disorders, such as autism spectrum disorder, cerebral palsy, epilepsy, attention-deficit hyperactivity disorder, impulse control disorder, depression, and anxiety. When an individual has the limited verbal ability, it can be challenging to identify and diagnose co-occurring conditions.

It is very important for family caregivers to be able to identify subtle changes in their loved ones. Anyone can lead a healthy and fulfilling life with the help of an accurate diagnosis and treatment.

What is the long-term outlook?

When ID comes with other severe medical issues, your kid may have a below-normal life expectancy. However, if your kid has mild to moderate ID, they will generally have a pretty typical life expectancy.

When your kid grows up, they may be able to perform a job that matches their level of ID, live independently, and support themselves.

Support services are available to assist people with ID to live independent and happy lives.

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