People with intellectual disability and mental illness: a forgotten minority

23 April 2018 | Posted In: #133 Autumn 2018, Disability Issues, Health Services, | Author: Thea Kremser | Author: Snow Li | Author: Erin Snelgrove | Author: Julian Trollor

In Australia, there are about 400,000 people with intellectual disability – that’s about two in every 100 Australians. Intellectual disability doesn’t often receive a lot of attention when we talk about mental health, but people with intellectual disability are seriously under-served in this area, explain Thea Kremser, Snow Li, Erin Whittle and Julian Trollor.

Many people don’t really know what it means to have intellectual disability. When someone’s intellectual ability lies in the lower range from an early age, and this impacts on every day social and practical skills, we call this intellectual disability. People with intellectual disability are a very diverse group, ranging from people with milder disability – who are largely independent, work and are in relationships – through to a much smaller group with very severe and multiple disabilities who need intensive support.

Compared to Australians in general, people with intellectual disability have very poor physical and mental health. People with intellectual disability die up to 27 years earlier than people without intellectual disability (1,2), and are much more likely to experience common illnesses and other disabilities. Mental illness is at least two to three times more common. Many people with intellectual disability experience relatively high levels of trauma, stigma and social isolation, poverty, financial and emotional strain on the family, and few opportunities to engage in a range of life choices. Intellectual disability often affects a person’s coping skills, communication skills and social skills. These factors all create stress and increase psychological vulnerability.

Despite this high rate of mental illness, people with intellectual disability are seriously disadvantaged when it comes to mental health support.  Instead of receiving consistent follow up and regular treatment in the community like other Australians, people with intellectual disability receive more one-off treatments, are more likely to visit emergency departments and psychiatric in-patient facilities, and are more likely to be misdiagnosed or receive an “unknown” diagnosis for their mental illness (3-4). Mental health professionals say they often don’t feel confident in supporting people with intellectual disability and need more training in this area (5).  Additionally, many state and national mental health policies don’t acknowledge people with intellectual disability. The disadvantage doesn’t end there. People with intellectual disability are disproportionately represented in the criminal justice system, and are on average only 15 years old when they have their first contact with police (6) – the youngest of any Australians. This often happens because of the person’s intellectual disability and untreated mental illness.

Overall, mental health and wellbeing for people with intellectual disability is poor, and people with intellectual disability experience multiple barriers to accessing high quality mental health treatments and supports. This places a lot of stress on carers leading to burn out, distress and financial hardship. When the person’s main support comes from a disability service it can mean that support workers feel overwhelmed and unable to meet the person’s needs, and the person ends up falling through the cracks without support or care.

When Australia ratified the UN Convention on the Rights of Persons with Disabilities in 2008, we agreed that people with intellectual disability have the right to the highest possible standard of health, without discrimination because of disability. However, this right is not being realised for many people with an intellectual disability and mental illness. Increasing our efforts to improve the situation for this significant minority is essential. There are a number of groups with key roles to play.

Federal and state governments

Governments need to start by acknowledging people with intellectual disability as a significant minority group, whose particular needs must be accounted for, in order to protect their human rights. Governments must formally consider the needs of people with intellectual disability in every health and mental health policy, and in every aspect of health services development.

State departments of health should make sure that all staff are trained to understand the mental health of people with intellectual disability, and to develop the skills they need to deliver mental health services to this group.


Primary health services, public and private mental health services, and specialised intellectual disability mental health services all share responsibility for mental health care of people with intellectual disability. Disability services and health services need to work in partnership, as many people require coordinated disability and mental health support. These services can significantly improve the quality of mental health care they provide by following these recommendations:

Taking a human rights approach

Public mental health services, in particular, need to recognise the mental health of people with intellectual disability as part of their core business, but all services should adopt a rights-based approach to mental health care of people with intellectual disability. Everyone involved in healthcare has an obligation to make sure that services are easy to access for people with intellectual disability.  This means assessing every level of a service for changes that would allow someone with intellectual disability to engage just as easily as someone without a disability does. Adjustments such as providing information in easy English, allowing longer appointments and training staff in disability-specific mental health knowledge and communication skills, can make a service more accessible for people with intellectual disability.

Developing relationships with other relevant agencies and services

All services should establish links with other agencies and services, including disability services and other mental health sectors. Collaborating means that it is easier to get into services, and easier for service providers to work together towards the most effective service possible.

Training their staff

Training is a vital part of ensuring all staff develop the necessary skills and knowledge to become confident in their ability to support people with intellectual disability.

Developing formal protocols and frameworks

Services are most likely to make the changes required if those changes are clearly written down. Services need to make formal decisions to take specific, concrete steps, and they need to communicate clearly with all their staff, so that everyone knows what principles and procedures to follow, and why.

The Department of Developmental Disability Neuropsychiatry (3DN) at UNSW was established in 2009 to improve health policy, practice and supports for people with intellectual or developmental disability, with a focus on mental health and wellbeing.  In The Guide, 3DN outlines steps that frontline service providers can take, in order to create accessible mental health services for people with intellectual disability. The Guide gives detailed, practical recommendations for creating the kinds of improvements detailed above. All mental health professionals and service providers are encouraged to embrace this responsibility to strive for equal access and to deliver the highest attainable standard of mental health care to people with intellectual disability.

Additional resources for services, carers, and professionals are available on the 3DN website at

Thea Kremser, Snow Li, Erin Whittle, Julian Trollor work at the Department of Developmental Disability Neuropsychiatry (3DN), UNSW Australia.


  1. Florio, T. and Trollor, J. (2015). “Mortality among a Cohort of Persons with an Intellectual Disability in New South Wales, Australia.” Journal of applied research in intellectual disabilities : JARID 28(5): 383.
  2. Trollor, J., et al. (2017). “Cause of death and potentially avoidable deaths in Australian adults with intellectual disability using retrospective linked data.” BMJ Open 6: e013489. doi:10.1136/bmjopen-2016-013489
  3. Howlett, S., et al. (2015). “Ambulatory mental health data demonstrates the high needs of people with an intellectual disability: Results from the New South Wales intellectual disability and mental health data linkage project.” N. Z. J. Psych. 49(2): 137-144.
  4. Lunsky, Y., et al. (2012). “Predictors of emergency department visits by persons with intellectual disability experiencing a psychiatric crisis.” Psychiatric Services 63(3): 287-290.
  5. Werner, S. and M. Stawski (2012). “Mental health: Knowledge, attitudes and training of professionals on dual diagnosis of intellectual disability and psychiatric disorder.” Journal of Intellectual Disability Research 56(3): 291-304.
  6. Baldry, E. Dowse, L. and Clarence, M. (2012) People with intellectual and other cognitive disability in the criminal justice system. Sydney, University of New South Wales.