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What is an Intellectual Disability?

26 Nov 2021

Intellectual disability is a term used when a person has limitations or difficulties with daily functions and mental capabilities, including the ability to learn, problem solve, and communicate. There are many types of intellectual disability, ranging from mild to severe, although more than half of those with an intellectual disability in Australia have a severe limitation on ‘core’ daily living activities.

According to the Australian Institute of Health and Welfare, over half a million Australians are living with an intellectual disability, representing approximately 3% of the population. Usually diagnosed in childhood, intellectual disabilities have a range of symptoms that vary from person to person and may be mild, moderate, or severe.

What causes intellectual disability?

There are many different causes of intellectual disability, many of which occur prior to birth. While there are some disabilities with clear causes, the cause of intellectual disability remains unknown in about 30-50% of cases.

Some known causes of intellectual disability include:

  • Genetic conditions
  • Environmental factors such as drugs, alcohol or toxins
  • Illnesses such as meningitis or measles
  • Head trauma
  • Issues during pregnancy and labour such as infection or not getting enough oxygen

What are some examples of intellectual disabilities?

There are a broad range of intellectual disabilities which manifest different signs and symptoms. In all conditions, symptoms vary from person to person, both in which symptoms are present, and in how severe they are. Here are some examples of intellectual disabilities and the common signs of each.

Down Syndrome

Down Syndrome is a genetic condition in which a person is born with an extra chromosome 21. Approximately 290 children, or one in 1,100, are born with Down Syndrome in Australia each year. Signs of Down Syndrome include:

  • Distinct physical characteristics
  • Some level of intellectual disability
  • A higher risk of respiratory and heart conditions
  • Some developmental delays

Prader-Willi Syndrome (PWS)

Prader-Willi Syndrome (PWS) is a rare genetic disorder in which the brain is unable to regulate appetite. Estimated to affect between 1 in 10,000 and 1 in 30,000 people, the defining symptom of PWS is an insatiable and excessive appetite. Other symptoms of PWS include:

  • Low body mass or obesity
  • Weak muscles
  • Intellectual disability and developmental delays
  • Anxiety and obsessive-compulsive behaviours

Symptoms of PWS can change over time and may increase or decrease in severity over a person’s lifetime. Learning to manage appetite is a crucial aspect of therapy and support in both children and adults with PWS.

Fragile X Syndrome (FXS)

Affecting 1 in 4,000 males and 1 in 6,000 females, Fragile X Syndrome (FXS) is an inherited genetic condition caused by a mutation in the X chromosome. FXS is the most common single-gene cause of autism, with many symptoms that link the two conditions. People with FSX may experience:

  • Developmental delay
  • Intellectual disability
  • Anxiety and ADHD
  • Sensory processing issues

Fetal Alcohol Spectrum Disorder (FASD)

Fetal Alcohol Spectrum Disorder (FASD) is a preventable condition caused by exposure to alcohol in the womb. When a pregnant woman ingests alcohol, the foetus is exposed to similar concentrations of alcohol as the mother, leading to significant impacts when the child is born. Symptoms of FASD vary greatly, but can include:

  • Distinctive facial features
  • Joint deformities
  • Organ damage, especially to the heart and kidneys
  • Delayed physical growth
  • Learning difficulties
  • Poor social skills and behavioural issues

Physical symptoms of FASD are rare, and the condition frequently goes undetected as the cognitive and behavioural symptoms are so varied. Children are often not diagnosed with FASD until their school years when symptoms become more noticeable, although many people are still misdiagnosed with other conditions.

Developmental Delay

Developmental delay is a term used when a child is slower than average in meeting developmental milestones. Although Developmental Delay is not classed as a disability on its own, the term Global Developmental Delay may be used when a child is delayed in 2 or more areas. Developmental delay can occur in any area of child development, including:

  • Speech and language
  • Gross motor skills such as walking and playing
  • Fine motor skills such as holding toys and drawing
  • Self-help skills
  • Social skills
  • Problem solving

There are a number of factors that may contribute to delayed development including being born prematurely, suffering chronic illness, or inheriting a disorder, although most of the time no cause is found. Depending on the severity of their delay, children may require minimal or extensive support, and if the delays are persistent, they may be diagnosed with another intellectual disability or condition.

Living with an intellectual disability can be challenging, but we’re here to help.

Contact us today to discuss the services we offer and how we can support your needs.


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