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  • Prevalence

    On this website 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.

    A program of surveys, the National Survey of Mental Health and Wellbeing (NSMHWB), began in Australia in the late 1990s. These surveys 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 8.5 million people based on the estimated 2015 popluation). It was also estimated that 1 in 5 (20%) of the population had experienced a common mental disorder in the previous 12 months (about 3.8 million people based on the estimated 2015 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%).

    For further information see the full NSMHWB report (ABS 2008).

    Survey of Children and Adolescents (aged 4–17)

    A national household survey of the mental health and wellbeing of Australian children and adolescents was conducted for the second time in 2013–14 ('Young Minds Matter').

    Almost 1 in 7 (13.9%) of children and adolescents aged 4–17 years were assessed as having mental health disorders in the previous 12 months, which is equivalent to about 575,000 children and adolescents. Attention Deficit Hyperactivity Disorder (ADHD) was the most common mental disorder (7.4% of all children and adolescents, or about 307,000 based on the estimated 2015 population), followed by Anxiety disorders (6.9% or about 286,000), Major depressive disorder (2.8% or  about 116,000) and Conduct disorder (2.1% or about 87,000)—see Figure 1.

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


    Figure 1: Prevalence of mental disorders in the past 12 months among those aged 4–17

    Bar chart showing the prevalence of mental disorders in the past 12 months in 4-17 year olds. ADHD was the most prevalent just over 7% followed by anxiety disorder just under 7%, major depressive disorder 3% and conduct disorder 2%

    Source: Lawrence et al. 2015.


    Child and adolescent males (16.3%) were more likely than females (11.5%) to have experienced mental disorders in the previous 12 months. The prevalence of mental disorders was slightly higher for older females (12.8% for 12–17 year olds) than for younger females (10.6% for 4–11 year olds). However, the prevalence for males did not differ markedly between the younger and older age groups (16.5% and 15.9% 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 three mental health disorders (Major depressive disorder, ADHD and Conduct disorder). Prevalence of Depressive disorder increased from 2.1% to 3.2%, ADHD decreased from 9.8% to 7.8%, and Conduct disorder decreased from 2.7% to 2.1%.

    Readers are directed to the full report for further information (Lawrence et al. 2015).

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

    Mental illness includes conditions with low prevalence and severe consequences.

    This group includes psychotic illnesses and a range of other conditions such as Eating disorders, and Severe personality disorder (DoHA 2010). Psychotic illnesses are characterised by fundamental distortions of thinking, perception and emotional response. Psychotic disorders include Schizophrenia, Schizoaffective disorder, Bipolar disorder and Delusional disorder (Morgan et al. 2011).

    Estimates from the 2010 NSMHWB Survey of People Living with Psychotic Illness were that 64,000 people in Australia aged 18–64 had 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 720,000 people based on the estimated 2015 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 2.5 million people) a mild disorder.

    Mental and behavioural disorders, such as Depression, Anxiety and Drug use, are important drivers of disability and morbidity. The Australian Burden of Disease Study 2011 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 2016). For Australia, Mental & substance use disorders were estimated to be responsible for 12.1% of the total burden of disease in 2011, placing it 3rd as a broad disease group after Cancer (18.5%) and Cardiovascular diseases (14.6%) (AIHW 2016).

    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 behavioural disorders were the largest contributor (23.6%) of the non-fatal burden of disease in Australia followed by Musculoskeletal disorders (22.7%) and Respiratory disorders (11.9%) (AIHW 2016).

    For further information see Australian Burden of Disease Study: Impact and causes of illness and death in Australia 2011.

    In addition, in 2013, almost a third (31%) of people in receipt of the Disability Support Pension had a primary medical condition of 'psychological/psychiatric' (DSS 2014).

    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 Survey of People Living with Psychotic Illness, people with 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).


    References

    Australian Bureau of Statistics (ABS) 2008. National survey of mental health and wellbeing: summary of results, Australia, 2007. ABS cat. no. 4326.0. Canberra: ABS.

    Australian Institute of Health and Welfare (AIHW) 2016. Australian Burden of Disease Study: Impact and causes of illness and death in Australia 2011. Australian Burden of Disease Study series no. 3. BOD 4. Canberra: AIHW.

    Department of Health and Ageing (DoHA) 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 Social Services (DSS) 2014. Characteristics of Disability Support Pension Recipients, June 2013. Canberra: DSS.

    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.


    Key concepts

    Overview of mental health services in Australia

    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 disability (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).