Intellectual disability and mental illness

In Australia, one in five people lives with a mental illness such as anxiety, depression, bipolar disorder or personality disorder.

This number is significantly higher for people with intellectual disability. Mental illness can remain undiagnosed because communication difficulties often make it harder for the person with intellectual disability to describe their feelings, concerns, experiences and fears.

Someone who lives with intellectual disability and mental illness is often referred to as having ‘dual disability’.

Dual Disability

There are several reasons that people with intellectual disability tend to have mental illness more often than other people in the community. They may have:

  • fewer friends and people to support them

  • more experience of loss, rejection or being separated from people

  • less control over their lives and lower self-esteem

  • homes where they do not feel comfortable or safe

  • experiences of bullying, abuse or neglect

  • trouble learning skills to help manage stress, solve problems or avoid conflict

  • a sensory disability including trouble seeing, hearing or using other senses.

Mental illness in people with intellectual disability can be overlooked because:

  • the person may find it hard to describe their feelings or experiences

  • the signs of illness may not be obvious or there all the time

  • the person may be taking medicines that affect their feelings or behaviour

  • it may be difficult to tell if the behaviour has happened in the past and to recognise patterns of mental illness

  • the symptoms may be similar to some types of disability, for example, autism spectrum disorder.