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Intellectual Disability

An intellectual disability is a condition in which children have a low level of intelligence (cognitive functioning) and deficits in their daily living skills (adaptive functioning) that have occurred in their developmental years (0 to 18 years of age) and that are expected to continue for life. This means that children with an intellectual disability have a significant delay in their learning and learn more slowly than their age-matched peers. The severity of an intellectual disability varies, from mild to severe. The way in which children with an intellectual disability function varies depending on the severity of their disability, the presence of other disabilities, their personality and coping skills, the amount of support they have and the expectations others have of them.

Approximately 2 % of children have an intellectual disability; most children with an intellectual disability have a mild disability. There are a number of causes of intellectual disability, including: genetic conditions (e.g., Down syndrome, Prader-Willi syndrome, Williams syndrome and Fragile X syndrome), medical conditions (eg. epilepsy), developmental disabilities (eg. Autism Spectrum Disorder), problems during pregnancy (e.g., chronic illness, lack of oxygen, injury, exposure to some medications, or exposure to drugs/alcohol), problems during birth (e.g., born extremely prematurely, lack of oxygen or injury), head or brain injury, environmental factors (e.g., lead or mercury poisoning), dietary factors (severe malnutrition or iodine deficiency) and some types of childhood illnesses (e.g., meningitis).

An intellectual disability is a lifelong disability. However, with appropriate structure, guidance and support, children with an intellectual disability can develop and learn over the course of their lives.

Characteristics of children with an intellectual disability

Preschool aged

Very young children who have concerns with their physical, behavioural, intellectual and/or social development that reach some of their developmental milestones more slowly than other children are often diagnosed with a developmental delay. Children having ongoing problems in several areas of their development may be diagnosed with a global developmental delay.

We know that children: develop at different rates, can develop in each of the areas of development at different rates, that delays in their developmental can be temporary and that there can be a number of reasons for their delays. Therefore we only consider diagnosing a more serious developmental disorder, such as an intellectual disability, when we know that a developmental delay has persisted and is affecting several areas of their development.

Further, we want to be thorough and accurate in our diagnosis of an intellectual disability, which means that we must use a number of assessment tools. To complete these assessments your child must have adequate language skills. For all of these reasons, we typically do not diagnose an intellectual disability until your child has adequate language skills and is approximately four years of age.

School aged

Your school aged child might have an intellectual disability, if s/he:

  • Learns more slowly than his/her peers
  • Processes information more slowly than his/her peers
  • Has trouble completing daily living skills (e.g., eating, dressing, bathing, going to the toilet, etc.)
  • Finds it difficult to problem-solve, plan and organise
  • Struggles with academic learning
  • Doesn’t understand abstract concepts (e.g., time and money)
  • Doesn’t easily understand what others say
  • Finds it difficult to answer questions
  • Acts awkwardly or inappropriately in social situations

Concerns for children with an intellectual disability

Children with an intellectual disability have different learning needs from those of their peers. In order to meet their needs, they must be identified as having an intellectual disability and provided with appropriate educational opportunities in a suitable school environment. It’s important to select a school that meets your child’s unique needs; some of the schooling options that might be available to a child with an intellectual disability are: being integrated (with support) in a mainstream classroom, being in a special education unit at a mainstream school, attending a specialist school or attending a special developmental school. In order to help children with an intellectual disability to perform to the best of their ability, teachers should use individualised learning plans to ensure that their specific learning needs are being met and provide appropriate accommodations and modifications.

Children with an intellectual disability are three times more likely than typically developing children to experience behaviour concerns and emotional concerns. They can also experience some specific behavioural concerns related to their intellectual disability, such as: acting aggressively towards others, hurting themselves, refusing to comply with boundaries and rules, demonstrating self-stimulating behaviours (e.g., hand mouthing), acting inappropriately in social situations (e.g., hugging strangers) and/or exhibiting inappropriate sexual behaviours (e.g., public masturbation).


Early identification and intervention have been shown to provide the best outcomes for children with an intellectual disability. If you believe that your child may have an intellectual disability, please visit our assessment page to learn more about the assessments we offer or contact us to schedule an appointment for an assessment.


Parents of children with an intellectual disability need to feel supported. You and your child will feel heard and understood at HMHK. We offer personalised, evidence-based treatments that can help make a difference in your child’s and your family’s lives. We can help your child if s/he is exhibiting challenging behaviours as a result of their experiences with having an intellectual disability. We can also help your child if they are experiencing other behaviour or emotional concerns. Please visit our treatment page for further information or contact us to schedule an appointment.

We can help your child if s/he has an intellectual disability and is experiencing negative outcomes at school by providing your child’s school with practical recommendations or by visiting your child’s school and meeting your child’s school professionals. Please contact us to schedule an appointment.