Prevalence and impact of mental illness Print this page

The National Study of Mental Health and Wellbeing of adults provides information on the 12-month and lifetime prevalence of mental disorders in the Australian population aged 16–85 years. Preliminary estimates from the first tranche of data from the 2020–21 study show that over 2 in 5 (44%) Australians in this age range experience a mental illness at some time in their life (about 8.6 million people). It also estimates that over 1 in 5 (21%) of the population experienced a mental disorder in the previous 12 months (about 4.2 million people).

Of these;

• Anxiety disorders (such as Social Phobia) were the most common, affecting 1 in 6 (17%) Australians
• Affective disorders (such as Depressive Episode) (8%)
• Substance Use disorders (such as Alcohol Dependence) (3%) (ABS 2022a)
  Full data are expected to be released in mid July 2023.

Intergenerational health and mental health study

The Intergenerational health and mental health study commenced in 2021. The latest Mental Health Study will update the estimates of the prevalence of mental illnesses from the 2007 National Survey of Mental Health and Wellbeing. It will provide updated statistics and insights into the impact of mental and behavioural and other chronic conditions on Australians and the use of health services and barriers to accessing them, as well as other health topics. The mental health component, The National Study commenced data collection for the first cohort in December 2020 (ABS 2021). Comprehensive data from the first phase of this study were published July 2022.

National Health Survey 2020–21

Another source of information about the mental health of Australians is the Australian Bureau of Statistics’ (ABS) National Health Survey (NHS) 2020–21, which provides information on a range of health conditions including mental and behavioural disorders. In contrast to the NSMHWB which uses a diagnostic instrument, the NHS estimates are based on self-reported information, and records a survey participant as having a mental or behavioural condition during the collection period only if it was also reported as long-term (had lasted, or was expected to last, a minimum of 6 months). The NHS 2020–21 estimated that 1 in 5 (20%) Australians reported that they had a mental or behavioural condition during the collection period (August 2020 to June 2021) (ABS 2022c).

A national household survey, the Australian Child and Adolescent Survey of Mental Health and Wellbeing, was conducted for the second time in 2013–14 (also referred to as the ‘Young Minds Matter’ survey). The findings highlight the most common and burdensome health condition in children and adolescents are mental illness which have significant adverse impacts on their academic outcomes.

Almost 1 in 7 (14%) children and adolescents aged 4–17 years were assessed as experiencing mental illness in the previous 12 months, which is equivalent to about 591,000 (based on the estimated 2017 population) children and adolescents.

Attention Deficit Hyperactivity Disorder (ADHD) was the most common mental illness (7% of all children and adolescents, or about 315,000 based on the estimated 2017 population) followed by,

• Anxiety disorders (7% or about 293,000)
• Major Depressive disorder (3% or about 119,000)
• Conduct disorder (2% or about 89,000)

Almost one third (30% or 4% of all 4–17 year olds) with a illness experienced 2 or more mental illnesses at some time in the previous 12 months.

Male children and adolescents (16%) were more likely than females (12%) to have experienced mental illness in the previous 12 months. The prevalence of mental illness was slightly higher for older females (13% for 12–17 year olds) than for younger females (11% for 4–11 year olds). However, the prevalence for males did not differ markedly between the younger and older age groups (17% and 16% respectively).

There were a number of significant methodological differences between the Young Minds Matter survey and the first child and adolescent survey conducted in 1998. However, it is possible to compare the prevalence data for 3 mental health illnesses (Major depressive disorder, ADHD and Conduct disorder). Prevalence of Depressive disorder increased from 2% to 3%, ADHD decreased from 10% to 8%, and Conduct disorder decreased from 3% to 2% (Lawrence et al. 2015).

Mental illness includes conditions with low prevalence and severe consequences, including psychotic illnesses and a range of other conditions such as eating disorders and personality disorders (DOH 2010). Psychotic illnesses may be characterised by symptoms including disordered thinking, hallucinations, delusions and disordered behaviour, and include Schizophrenia, Schizoaffective disorder, and Delusional disorder.

Estimates from the 2010 National Psychosis Survey were that 64,000 people in Australia aged 18–64 experienced a psychotic illness and were in contact with public specialised mental health services each year. This equates to 5 cases per 1,000 population. The survey found the most frequently recorded of these disorders was Schizophrenia which accounted for almost half of all diagnoses (47%) (Morgan et al. 2011).

For the first time, the Census of Population and Housing (the Census) conducted in 2021 asked Australians about 10 common long-term health conditions. Over 8 million (about 32%) Australians reported that they had been diagnosed with a long-term health condition, with 2.2 million (about 9%) reporting a Mental health condition (including depression or anxiety) (ABS 2022b).

The ABS recommends that the NSMHWB be used as the main source of prevalence data as it uses diagnostic criteria rather than self-reporting as with the Census. Visit Comparing ABS long-term health conditions data sources for more information.

In 2018–19, among the total Indigenous Australian population, an estimated 24% (187,500) reported a mental health or behavioural condition, with a higher rate among females than males (25% compared with 23%, respectively). An estimated 31% reported experiencing high or very high levels of psychological distress in the previous 4 weeks (ABS 2019). More information can be found at Australia’s health 2020 – Indigenous health and wellbeing.

Lesbian, gay, bisexual, transgender, intersex, queer/questioning and asexual Australians report lower health and wellbeing compared to Australians generally. A survey of LGBTIQA+ Australians, the Private Lives survey, has been conducted 3 times since 2005. The most recent survey, undertaken in 2020, attracted about 6,800 participants. Three fifths (61%) report having been diagnosed with depression and almost half (47%) with an anxiety disorder, while over half (57%) report experiencing high or very high levels of psychological distress within the past 4 weeks. Furthermore, only 59% of people who accessed a mainstream medical clinic felt that their sexual orientation was very or extremely respected, and only 38% thought that their gender identity was very or extremely respected (Hill et al. 2020). More information can be found at Private Lives 3.

Adults with disability generally experience higher psychological distress than those without disability. In 2017–18, it was estimated that 32% of adults with disability experienced high or very high psychological distress in the previous week, compared to 8% of the population without disability. People with psychological disability were the most likely to report high or very high psychological distress (76%), followed by people with intellectual disability (60%) (AIHW 2020). More information can be found at People with disability in Australia.

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ABS (2021) Household Impacts of COVID-19 Survey – March 2021 release. ABS cat. No. 4940.0, ABS, Canberra.

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AIHW (2021) Australian Burden of Disease Study: Impact and causes of illness and death in Australia 2018, Cat. no. BOD 29, accessed 9 March 2022.

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DoHA (Department of Health and Ageing) (2010) National mental health report 2010: summary of 15 years of reform in Australia’s mental health services under the National Mental Health Strategy 1993-2008, DoHA, Canberra.

Hill AO, Bourne A, McNair R, Carman M and Lyons A (2020) Private Lives 3: The health and wellbeing of LGBTIQ people in Australia, ARCSHS Monograph Series No. 122, Australian Research Centre in Sex, Health and Society, La Trobe University, Melbourne.

Lawrence D, Hancock K and Kisely S (2013) ‘The gap in life expectancy from preventable physical illness in psychiatric patients in Western Australia: retrospective analysis of population based registers’. British Medical Journal, 346, accessed 9 March 2022.

Morgan VA, Waterreus A, Jablensky A, Mackinnon A, McGrath JJ, Carr V, Bush R, Castle D, Cohen M, Harvey C, Galletly C, Stain HJ, Neil AL, McGorry P, Hocking B, Shah S and Saw S (2011) People living with psychotic illness 2010: the second Australian national survey of psychosis, accessed 8 March 2022.

Productivity Commission (2020) Productivity Commission Inquiry – Mental Health Report no.95, Productivity Commission, Canberra.

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WHO (2021) Mental health: strengthening our responses, WHO, accessed 3 August 2022.