Prevalence, impact and burden

Prevalence

In the Mental health services in Australia online report, the terms ‘mental illness’ and ‘mental disorder’ are both used to describe a wide spectrum of mental health and behavioural disorders, which can vary in both severity and duration. The most prevalent mental illnesses in Australia are Depression, Anxiety and Substance use disorders (ABS 2008).

A program of surveys, the National Survey of Mental Health and Wellbeing (NSMHWB), began in Australia in the late 1990s. The role of these surveys is to provide evidence on the prevalence of mental illness in the Australian population, the amount of disability associated with mental disorders, and the use of health services by people with mental disorders. These studies have 3 main components—a population-based survey of adults, a service-based survey of people with psychotic disorders, and a population-based survey of children.

Survey of Adult Population (aged 16–85)

The 2007 National Survey 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. The survey estimated that almost half (45%) of the population in this age range will experience a mental disorder at some time in their life (about 8.7 million people based on the estimated 2017 population). It also estimated that 1 in 5 (20%) of the population had experienced a common mental disorder in the previous 12 months (about 3.9 million people based on the estimated 2017 population). Of these, Anxiety disorders (such as social phobia) were the most prevalent, afflicting 1 in 7 (14.4%) of the population, followed by Affective disorders (such as depression) (6.2%), and Substance use disorders (such as alcohol dependence) (5.1%). Further information can be found in the full NSMHWB report(ABS 2008).

The Intergenerational Health and Mental Health Study is scheduled to be undertaken from 2020 by the Australian Bureau of Statistics. The Mental Health Study will measure the prevalence of mental illnesses for the first time since 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 (ABS 2019a).

Another source of information about the mental health of Australians is the ABS’s National Health Survey 2017–18, 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 National Health Survey estimates are based on self-reported data, and record 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) (ABS 2019b). The National Health Survey 2017–18 estimated that 1 in 5 (20%) Australians reported that they had a mental or behavioural condition during the collection period (July 2017 to June 2018).

Survey of Children and Adolescents (aged 4–17)

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).

Almost 1 in 7 (13.9%) children and adolescents aged 4–17 years were assessed as experiencing mental health disorders 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 disorder (7.4% of all children and adolescents, or about 315,000 based on the estimated 2017 population), followed by Anxiety disorders (6.9% or about 293,000), major Depressive disorder (2.8% or about 119,000) and Conduct disorder (2.1% or about 89,000)— see Figure 1.

Almost one third (30.0% or 4.2% of all 4–17 year olds) with a disorder experienced 2 or more mental disorders at some time in the previous 12 months.

 
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Description of figure 1

Survey of People Living with Psychotic Illness (aged 16–84)

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 (DoHA 2010). Psychotic illnesses may be characterised by symptoms including disordered thinking, hallucinations, delusions and disordered behaviour, and include Schizophrenia, Schizoaffective disorder, and Delusional disorder (Morgan et al. 2011).

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 or 0.5% of the population (Morgan et al. 2011). The survey found the most frequently recorded of these disorders was Schizophrenia which accounted for almost half of all diagnoses (47.0%). Readers are directed to the full report for further information.

Impact and burden

Mental disorders can vary in severity and be episodic or persistent in nature. A recent review estimated that 2–3% of Australians (about 615,000 people based on the estimated 2017 population) have a severe mental disorder, as judged by diagnosis, intensity and duration of symptoms, and degree of disability caused (DoHA 2013). This group is not confined to those with psychotic disorders and it also includes people with severe and disabling forms of depression and anxiety. Another 4–6% of the population (about 1.2 million people) are estimated to have a moderate disorder and a further 9–12% (about 2.6 million people) a mild disorder.

Mental and substance use disorders, such as Depression, Anxiety and Drug use, are important drivers of disability and morbidity. The Australian Burden of Disease Study 2015 examined the health loss due to disease and injury that is not improved by current treatment, rehabilitative and preventative efforts of the health system and society (AIHW 2019a). For For Australia, Mental and substance use disorders were estimated to be responsible for 12% of the total burden of disease in 2015, placing it fourth as a broad disease group after Cancer (18%), Cardiovascular diseases (14%) and Musculoskeletal conditions (13%) (AIHW 2019a). Further information can be found in the Australian Burden of Disease Study: Impact and causes of illness and death in Australia 2015.

In terms of the non-fatal burden of disease, which is a measure of the number of years of ’healthy’ life lost due to living with a disability, Mental and substance use disorders were the second largest contributor (23%) of the non-fatal burden of disease in Australia, behind Musculoskeletal conditions (25%) (AIHW 2019a). In addition, in June 2018, about a third (34%) of people in receipt of the Disability Support Pension had a primary medical condition of ‘psychological/psychiatric’ (AIHW 2019b).

There is an association between diagnosis of mental health disorders and a physical disorder, often referred to as a ‘comorbid’ disorder. From the 2007 NSMHWB of adults, 1 in 8 (12.0%) of people with a 12-month mental disorder also reported a physical condition, with 1 in 20 (5.0%) reporting 2 or more physical conditions.

According to the 2010 National Psychosis Survey, people with a psychotic illness also frequently experience poor physical health outcomes and comorbidities (Morgan et al. 2011). For example, over one-quarter (27%) of survey participants had heart or circulatory conditions and over one-fifth (21%) had diabetes (compared with 16% and 6% respectively in the general population). The prevalence of Diabetes found in the National Survey of People Living with Psychotic Illness is more than 3 times the rate seen in the general population. Other comorbidities included Epilepsy (7% compared with 0.8% in the general population) and Severe headaches/migraines (25% compared with 9% in the general population).

Psychological distress

Another insight into the mental health and wellbeing of Australians is provided by measures of psychological distress. Psychological distress can be described as unpleasant feelings or emotions that affect a person’s level of functioning and interfere with the activities of daily living. This distress can result in having negative views of the environment, others and oneself, and manifest as symptoms of mental illness, including anxiety and depression. The Australian Bureau of Statistics (ABS) measures psychological distress in the National Health Survey (NHS) using the Kessler 10 (K10) psychological distress scale measuring non-specific psychological distress, based on questions about negative emotional states experienced in the past 30 days (ABS 2012).

In 2017–18, 13% or 2.4 million Australians aged 18 and over experienced high or very high levels of psychological distress, a 12% increase from 2014–15 (11.7% or 2.1 million Australians). High or very high levels of psychological distress were more often reported by women than men in 2017–18 (15% and 11% respectively). Of all age groups, young people (aged 18–24) were most likely to experience high or very high levels of psychological distress (15.2%) (ABS 2019b).


References

ABS (Australian Bureau of Statistics) 2008. National Survey of Mental Health and Wellbeing: summary of results, Australia, 2007. ABS cat. no. 4326.0. Canberra: ABS.

ABS 2012. Information paper: Use of the Kessler Psychological Distress Scale in ABS health surveys, Australia, 2007-08. ABS cat. no. 4817.0.55. Canberra: ABS.

ABS 2019a. Australian Bureau of Statistics – Forward Work Program, 2019-20. ABS cat. No. 1006.0. Canberra: ABS.

ABS 2019b. National Health Survey: first results, 2017-18. ABS cat. no. 4364.0.55.001. Canberra: ABS.

AIHW (Australian Institute of Health and Welfare) 2019a. Australian Burden of Disease Study: impact and causes of illness and death in Australia 2015. Australian Burden of Disease Study series no. 19. Cat. no. BOD 22. Canberra: AIHW.

AIHW 2019b. People with disability in Australia. Cat. No. DIS 72. Canberra: AIHW

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. Canberra: Commonwealth of Australia.

DoHA 2013. National Mental Health Report 2013: tracking progress of mental health reform in Australia 1993 – 2011. Canberra: Commonwealth of Australia.

Department of Health 2020. Medicare Benefits Schedule Book, effective March 2020. Canberra: Department of Health.

Lawrence D, Johnson S, Hafekost J, Boterhoven De Haan K, Sawyer M, Ainley J, Zubrick SR 2015. The Mental Health of Children and Adolescents. Report on the second Australian Child and Adolescent Survey of Mental Health and Wellbeing. Canberra: Department of Health.

Morgan VA, Waterreus A, Jablensky A, Mackinnon A, McGrath JJ, Carr V, et al. 2011. People living with psychotic illness 2010. Canberra: Australian Government Department of Health and Ageing.


Description of Figure 1

Vertical bar chart showing the prevalence of mental disorders in the past 12 months among those aged 4- 17. ADHD was the highest with 17. 7% followed by Anxiety disorder 6.9%, Major depressive disorder 2.8% and Conduct disorder 2.1% Back to figure 1


Key concepts

Key concept Description
Burden of disease Burden of disease is measured in disability-adjusted life years (DALYs)—years of life lost due to premature mortality (fatal burden) and years of healthy life lost due to poor health (non-fatal burden).
Comorbidity Comorbidity refers to occurrence of more than one condition/disorder at the same time.
Prevalence Prevalence measures the proportion of a population with a particular condition during a specified period of time (period/point prevalence), usually measured over a 12-month period or over the lifetime of an individual (lifetime prevalence).