Intellectual Disability

Disclaimer: This fact sheet is for education purposes only. Please consult with your doctor or other health professional to make sure this information is right for your child.

What is intellectual disability?

When a child has a significant delay in learning and this delay affects several areas of a child's development (global delay) and is expected to continue for life, then professionals start to talk about a child having an intellectual disability.

Intellectual disability is defined as "low general intellectual functioning as measured by an Intelligence Quotient Score (IQ), before a child is 18 years old". An affected individual is significantly behind their age related peers in acquiring new skills required for academic learning and daily activities. The degree of impairment can vary significantly and is classified as "mild, moderate, severe or profound". Around the world, different terms are used for intellectual disability, for example in the USA professionals talk of a child having mental retardation.

How is a child diagnosed with intellectual disability? Children vary enormously in their rate of development. If you have concerns regarding your child's development, talk to your early childhood nurse, teacher, family doctor or paediatrician. Reasons why parents or professionals may suspect an intellectual disability include a history of developmental delay or a child having ongoing learning difficulties at school.

For a child to be diagnosed as having an intellectual disability, they will require a formal assessment, which is done by a psychologist or a school counsellor. This involves gathering information about a child from their parents, child-care centre or school, therapists and doctor as well as observation and interaction with the child. Formal intellectual (IQ) testing may include a series of tasks such as naming pictures, completing puzzles and problems and answering questions.

What can be done to help?

Children with an intellectual disability will continue to learn and develop new skills, but at their own pace. They will often need more time and practice than other children of the same age.

Once a diagnosis of an intellectual disability is made, a child may get additional support at school and home, to help them learn to their best potential. There are many options for education including additional help in a mainstream class, a special unit within a mainstream school or a school specially designed for children with intellectual disabilities. Speech therapists, occupational therapists and psychologists can give extra support at school or at home.

Children with intellectual disabilities are all different - some will require support in living independently in the community, others will live independent lives with perhaps only some difficulties in reading and writing. Having a child diagnosed with an intellectual disability can be upsetting for the family, who may feel they need to make different plans for the future.

All children have their own strengths and weaknesses. Building self esteem is important for confidence to learn new skills

What causes intellectual disability?

There are many possible causes for children having intellectual disabilities, but most often no cause is found. Causes may include:

  • genetic conditions- for example Down syndrome or fragile X syndrome
  • an injury to the head or brain
  • some types of infection, such as meningitis
  • chronic illnesses or drug/ medication use before the baby is born
  • problems around the time of birth

It is important that your child be thoroughly examined by your family doctor or paediatrician to discuss a possible cause and other associated conditions.

What support is there?

Many services can provide support and information to families:


  • Children with intellectual disability vary in their ability to learn and in their long term outcome. Other factors such as personality, presence of other disabilities and social support also play an important role in how much a child is able to learn
  • The earlier a child is diagnosed with intellectual disability and supports put in place the better the outcome for the child
  • It is important to find individual strengths and applaud achievements
  • Many services are available to support people with disabilities and their families.
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