Figure 2: Types of serious illness by age and sex, 2009 to 2021

Mental illness includes conditions with relatively low prevalence and potentially severe consequences, such as psychotic illnesses (Department of Health and Ageing 2010). Psychotic illnesses may be characterised by symptoms including disordered thinking, hallucinations, delusions and disordered behaviour, although individual experiences vary greatly. Diagnoses include Schizophrenia, Schizoaffective disorder and Delusional disorder.

The 2010 National Psychosis Survey estimated that 64,000 Australians aged 18–۶۴ 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).

Change over time

Prior to 2020–۲۰۲۲, the NSMHW was last undertaken in 2007. Between the two surveys, prevalence of mental illness among the Australian population remained broadly similar, with 45% of Australians aged 16–۸۵ years having a lifetime mental disorder in 2007, compared with 43% in 2020–۲۰۲۲٫ In 2007, an estimated 20% of Australians had a 12-month mental disorder, compared with 22% in 2020–۲۰۲۲٫

Between the two surveys, the prevalence of a 12-month mental disorder remained the same among males (18% for both), but there was an increase among females (from 22% in 2007 to 25% in 2020–۲۰۲۲).

While the prevalence of a 12-month mental disorder remained broadly similar between the two surveys for people aged 25–۸۵, there was a , 26% of those aged 16–۲۴ had a 12-month mental disorder; in 2020–۲۰۲۲, this figure was 39%. This change is almost entirely driven by an increased prevalence of mental illness among females in this age group: 30% of females aged 16–۲۴ years in 2007 had a 12-month disorder, compared with 46% in 2020–۲۰۲۲ (the prevalence for males of this age group increased from 23% to 32%).

Changes in methodology and diagnostic criteria mean that some comparisons between the 2007 and 2020–۲۰۲۲ studies should be made with caution. For more information, refer to Data interpretation.

Age and sex

Prevalence of mental illness varies by age and sex. Mental illness prevalence has increased more rapidly than prevalence of other serious illnesses; this increase has been more pronounced for young women (aged 15–۳۴). In 2021, double the proportion of females aged 20–۲۹ reported that they had been told by a doctor or nurse that they have a mental health condition compared to males the same age (16% and 8%, respectively) (ABS 2022a)

According to the HILDA survey, in 2021, the estimated prevalence of depression or anxiety was highest among younger women and men (aged 15–۳۴) at 22%, compared to 15% for people aged 55 and over. Since 2017, mental illness prevalence rates exceed asthma, which had been the most common serious illness for this age group (Figure 2).

Line graph showing estimated prevalence of serious illnesses in Australia by sex and age group. Figures available for 2009, 2013, 2017, 2020 and 2021. Depression or anxiety have the highest prevalence rate in Australia among all serious illnesses included in the HILDA survey in 2020 and 2021.

The HILDA Survey provides data which allows the persistence of serious illness to be considered. The 2021 survey results showed that:

• ۶۱% of males who were diagnosed with depression or anxiety in 2017 reported still having the condition 4 years diferenГ§as entre mulheres canadenses e americanas later.
• ۷۱% of females who were diagnosed with depression or anxiety in 2017 reported still having the condition 4 years later.
• ۷۰% of people aged 15–۳۴ who were diagnosed with depression or anxiety in 2017 reported still having the condition 4 years later.
• ۶۹% of people aged 35–۵۴ who were diagnosed with depression or anxiety in 2017 reported still having the condition 4 years later.