Description of intellectual disabilities
There are many definitions used to explain, define and determine an intellectual disability, but each is often
limited in providing an accurate representation of this particular disability. An intellectual disability
should not be confused with a psychiatric disability or mental illness, although a person with an intellectual
disability may also have a psychiatric disability.
Examples of intellectual disability
- Down syndrome
- developmental disability
Examples of psychiatric disability/mental illness include:
- anxiety disorders
- bipolar disorder (manic depression)
- post traumatic stress disorder
While definitions of intellectual disabilities may provide some insight into the disability itself, it is important
that these definitions do not label the person and that generalised assumptions are not made.
A person with an intellectual disability may also have a print disability, hearing
impairment or physical disability.
Intellectual disability (mental retardation) is described by the (DSM-IV) Diagnostic and Statistical
Manual of Mental Disorders as the presence of a sub-average general intellectual functioning associated with
or resulting in impairments in adaptive behaviour. The onset of this disability
occurs before the age of 18.
The level of intellectual disability is classified by intelligence quotient (IQ)
scores and ranges from mild to profound. A person with an intellectual disability may:
have difficulty with both expressive and receptive language (that is both
speaking and understanding what is being communicated)
- have a physical disability
- have difficulty in learning and concentrating
- display behaviour that would appear to be inappropriate
- may be unable to read or write
- may be unable to live independently
- may have difficulty in participating in group settings
There is a high incidence of epilepsy among people with an intellectual
C A U S E S A N D P R E V A L E N C E
Causes of intellectual disabilities are many. They include an abnormal number
of chromosomes, gene defects, maternal infections, Rh incompatibility, head trauma, anoxia, birth injury, early infant
infection and, deprived normal development and growth experiences.
Intellectual disability is twice as common in males as in females. It is estimated that 2.3 percent of the
Australian population have some level
of intellectual disability. In the state of Victoria it is believed that approximately
one percent of the population has some level of intellectual disability, with the
Department of Human Services being aware of 60 percent of these people.
F U N C T I O N A L I M P L I C A T I O N S F O R
E V E R Y D A Y L I V I N G
The inability to process information and effectively communicate with other
people is possibly the most notable implication for every day living. As communicating is often taken for
granted by most members of society, people with an intellectual disability can struggle to express their needs.
A deficit in intellectual functioning and associated disabilities can
have a significant effect on an
individual's education, leisure, employment and social and personal opportunities.
S E R V I C E S, A I D S, I N T E R V E N T I O N S
There are many services and aids available to people with an intellectual
disability to help and encourage them to live more independently and to offer
the least restrictive of services.
One of the stated principles of the Intellectually Disabled Persons' Services
Act, (1986) is that:
"services generally available to all members of the community should
be adapted to ensure access by intellectually disabled persons and specialised supplementary services
should be provided to the extent required to meet individual needs"
Services of assistance include:
- residential / accommodation
- vocational training
- Individual Program Plan development
- personal care
- individual needs assessment
Aids which can assist include:
- communication boards / books
- walking aids
- talking books
The resource guide lists organisations which are able to assist with information relating to the provision
of these aids and services.
Below are listed some common examples of conditions which may be described as intellectual
D O W N S Y N D R O M E
Down syndrome is a genetic condition caused by extra genetic material (genes)
from the 21st chromosome. Varying degrees of intellectual disability are associated with Down syndrome. They
can range from mild to severe.
Down syndrome takes its name from the British doctor, John Langdon Down, who
first clinically identified the condition in 1866. There is an increased risk of
having a child with Down syndrome if the mother's age is over 35 years.
It is not known what causes the extra 21st chromosome, but the association
with the mother's age is well documented. There is a number of tests now used for diagnostic purposes and
Some of the physical traits that are common but not always present are epicanthal folds over the eyes, flattened
bridge of the nose, a single palmar crease and decreased muscle tone.
A U T I S M
Autism is a developmental disability that typically appears during the first
three years of life. The result of a neurological disorder that affects the functioning of the brain, autism and
its associated behaviours occur in approximately 15 of every 10,000 individuals.
Autism is four times more prevalent in boys than girls and knows no racial, ethnic or social boundaries.
Socio-economic, lifestyle and educational levels do not affect the possibility of its occurrence.
Autism interferes with the normal development of the brain in areas of reasoning, social interaction and
communication skills. Children and adults with autism typically have deficiencies in verbal and non-verbal
communication, social interactions and leisure or play activities.
The prevalence of autism now rates as the third most common developmental
disability - more common than Down syndrome. Although the cause of autism is not known, current research links
autism to biological or neurological differences in the brain.
The prevalence of autism now rates as the third most common developmental disability
- more common than Down Syndrome
D E V E L O P M E N TA L D I S A B I L I T Y
A developmental disability is a disability that is manifested before the person
reaches 22 years of age, which constitutes a substantial disability and is attributed to mental retardation
or related conditions which include cerebral palsy, epilepsy and autism.
Developmental delay is the slowed or impaired development of a child who is under five years old and who is at
risk of having a developmental disability because of one or more of the following:
- chromosomal conditions associated with mental retardation
- congenital syndromes and conditions
- associated with delay in development
- prenatal and perinatal infections and significant medical
- low birth weight infants weighing less than 1,200 grams