What is Intellectual Disability?

In 2012 the Australian Bureau of Statistics reported that approximately 2.9% of the population had a diagnosed Intellectual Disability.

In first discussing Intellectual Disability (ID) it is important to know that children, teenagers and adults can and do learn new skills. ID is however referred to as having a below average intelligence quotient (IQ) that affects the individuals’ ability to manage day to day activities with an onset before 18 years of age.

What is Intellectual Disability and are there types of intellectual disability? Intellectual Disability is an IQ that is assessed at below 70 which has a limiting effect on a person’s’ capacity to function in comparison to their same age peers.


There are types of intellectual disability as identified in the Diagnostic Statistical Manual IV(DSM IV).  Severity of disability is identified as follows:

Mild: IQ level 50-55 to approximately 70

Moderate: IQ level 35-40 to 50-55

Severe: IQ level 20-25 to 35-40

Profound: IQ level below 20-25

Boys aged 0-14 years are twice as likely to have intellectual disability than girls in the same age group. This is possibly due to the fact that boys have higher rates of some conditions that are more commonly associated with intellectual disability. For example, boys in this age group were 3.6 times more likely to have Autism Spectrum Disorder  or a related disorder than girls, 50,500 boys compared with 13,900 girls.

A person with ID has limitations within at least two areas of their daily functioning. These are:

  • Capacity for intellectual functioning, referred to as IQ, which indicates the level at which a person can learn, reason, make decisions and solve problems on a daily basis.
  • Adaptive behaviour which refers to the ability to function daily for such things as self-care, communication and the ability to have interactions with other people.

The severity of the disability may be obvious early in infancy or if it is mild it may in fact not be identified until a young child commences school. Some of the signs to be aware of are:

  • The young child may be late to roll over, sit up, crawl or walk
  • They may have trouble talking or be late to talk
  • They may not appear to understand what others are saying
  • Simple skills such as getting dressed, feeding themselves and being toilet trained may not be achieved
  • They may have trouble interacting with children of the same age
  • They may show difficulty in remembering things and problem solving
  • They may not demonstrate an understanding of the consequences of their actions and could be prone to more childhood tantrums than is typical

Intellectual disability can present very differently for many children, teenagers and adults. There are however a range of interventions and supports to assist learning and each individual’s’ capacity to manage the functions of daily life. Within this website you will be assisted to navigate this journey with your child.