Intellectual Disability

Intellectual disability is a developmental disorder that occurs before the age of 18 years old and is characterised by significantly below-average intellectual functioning and deficits in adaptive functioning.

Behaviour Help is a registered NDIS provider.

positive adult women discussing intellectual disability

Definition of Intellectual Disability

According to the Diagnostic and Statistical Manual of Mental Disorders (DSM-V), intellectual disability is a developmental disorder that occurs before the age of 18 years old and is characterised by significantly below-average intellectual functioning and deficits in adaptive functioning (e.g. communication, social participation, education, play/leisure and activities of daily living) (American Psychiatric Association, 2013; Parekh, 2017).


Causes of Intellectual Disability

The causes of intellectual disability are categorised on the basis of when they occur in the developmental period, i.e. before birth, during birth, or after birth. Some of the identified causes include: 

  • Before birth: genetic causes, exposure to maternal infection, alcohol, or drugs 
  • During birth: prematurity, low birth weight, and various labour/delivery-related events
  • During childhood: complications from infectious diseases, accidental injury to the brain, and poverty


Types of Intellectual Disability

Individuals with intellectual disabilities are often placed into levels to reflect the severity of their intellectual and adaptive functioning impairment (APA, 2013). These levels include:

  • Mild (Intelligence Quotient (IQ)) Score Range: 50 – 70) 
  • Moderate (Intelligence Quotient (IQ)) Score Range: 35 – 49) 
  • Severe (Intelligence Quotient (IQ)) Score Range: 20 – 34) 
  • Profound (Intelligence Quotient (IQ)) Score Range: Less than 20)



For an individual to be diagnosed with an intellectual disability, the following three criteria must be met: 

Criteria 1 – deficits in intellectual functioning (intelligence) 

This includes various mental abilities:

  • Reasoning
  • Problem solving
  • Planning
  • Abstract thinking
  • Judgment
  • Academic learning (ability to learn in school via traditional teaching methods)
  • Experiential learning (the ability to learn through experience, trial and error, and observation)

Criteria 2 – deficits in adaptive functioning

Adaptive functioning refers to a collection of skills in communication, social, conceptual, personal independence, school or work functioning that enables the individual to cope with common life demands, and function independently, effectively, and as expected in an age-appropriate manner (American Psychiatric Association, 2013). 

These limitations occur during the developmental period. This means problems with intellectual or adaptive functioning were evident during childhood or adolescence.



American Psychiatric Association (2013). Diagnostic and Statistical Manual of Mental Disorders (5th ed.).

Parekh, R. (2017). What is Intellectual Disability?



Behaviour Help

If you are supporting an individual with this diagnosis, please refer to our services and resources. They aim to help children, adolescents and adults achieve better communication, social, emotional, behavioural and learning outcomes. So whether you are wanting guidance on parenting, teaching, supporting or providing therapy, Behaviour Help is at hand.

Note: This is not an exhaustive list of all the possible causes, symptoms and types but some general information that can be further explored. Based on what you have read if you have any concerns about an individual, please raise them with the individual/s. The caregiver can then raise these concerns with their local doctor who can provide a referral to the relevant professional (e.g. paediatrician, psychologist, psychiatrist, allied health professional and learning specialists) for diagnosis and treatment if appropriate.

Which resources are right for you?


Based on the Taking CHARGE of Rainbow of Emotions Workbook this app helps children of all ages develop emotional regulation skills. The app guides the child to firstly, identify and express their emotion in appropriate ways. Then the child is guided to use emotional management tool/s from the CHARGE tool kit to manage their emotions in a healthy way.

The acronym CHARGE stands for the different categories of emotional management tools – Chat tools, Helpful thinking tools, Amusement tools, Relaxation tools, Good routine tools and Exercise tools.

Behaviour Help App - Using the evidence-based approach of Positive Behaviour Support (PBS), the Behaviour Help web-based app allows people supporting individuals with emotional and behavioural difficulties to complete a Functional Behaviour Analysis and put together a comprehensive Behaviour Support Plan (BSP). The BSP can then be used by everyone interacting with the individual to manage and prevent challenging behaviours and ultimately improve their lives, and the lives of those who support them.


If you want to learn more about emotional and behavioural difficulties then we have a great range of books you can read on your Kindle or order from Amazon.


Personalised and practical one to one help tailored specifically to your family.

Online Courses

Access these online courses anytime online to learn about a range of diagnoses, practical skills and strategies to help develop the individual’s emotional regulation skills. Also learn to utilise the positive behaviour support framework to address anxiety, aggression, ADHD, ASD and ODD.

SEL Educational Videos

Minimise or eliminate the occurrence of challenging behaviours by teaching children of all ages appropriate ways of communicating, interacting, managing their emotions and behaviours.

The SEL curriculum uses video modelling to provide direct, explicit and systematic teaching of the various skills by discussing the importance of the skill, modelling the skill so the child learns what the skill looks like? sounds like? feels like? and learn the skill in staged situations that simulate real life scenarios.


Personalised and practical behaviour therapy tailored specifically to your family.


Webinars discuss a range of practical strategies to guide your child learn positive ways of behaving and managing their emotions.


Attend our practical and interactive workshops to learn about a range of diagnoses, practical skills and strategies to help develop the individual’s emotions, behaviours, social and communication skills in your learning environment.

Ask Dolly

Since you’re here, you probably have questions and concerns. I am Dolly Bhargava, am here to help. I am a NDIS registered behaviour support practitioner and speech pathologist.

I have worked in a number of settings for over 21 years so, how can I help?

Please tell me what is worrying you right now and I will do my best to recommend resources and/or services that will be most useful to you in your situation.

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