• One in five Australian adults experience a mental illness every year.
  • About 45 per cent of Australian adults will be affected by mental illness at some time in their life.
  • Anxiety, mood disorders (such as depression) and substance use disorders are the most common mental illnesses experienced by Australian adults.

Mental illness is common. One in five Australians experience mental illness every year, and 45 per cent of Australian adults will be affected by mental illness at some time in their life. 

Types of mental illness

Mental illness is a general term that refers to a group of illnesses that affect the brain. A mental illness is a health problem that significantly affects how a person feels, thinks, behaves, and interacts with other people. Mental illnesses are diagnosed according to standardised criteria. 

The symptoms of mental illness may interfere with people's lives in different ways and to different degrees. The severity of mental disorders can be classified as mild, moderate or severe. This is based on what impact the symptoms have on someone’s home management, social life, ability to work and relationships.

The most common types of mental illness affecting Australians include:

  • mood disorders (also known as affective disorders), such as depression and bipolar disorder 
    • In 2017–18, about 10% of Australians experienced depression or feelings of depression (11.6% of women and 9.1% of men were affected by depression)
    • Bipolar I disorder may be experienced by up to 1% of Australians over their lifetime. The lifetime risk of bipolar II disorder is up to 5%
  • anxiety disorders – in 2017, anxiety disorders affected 13% of the population
  • psychotic illness – such as schizophrenia. In 2010, the second national survey of psychotic illness in found that about 0.4% of Australians (around 64,000 people) are affected by psychotic illness.

Living with more than one mental illness

Some people are affected by more than one mental illness. In 2017 in Australia, around 6% of people living with an anxiety disorder were also experiencing depression (1.5 million people).

Mental illness and increased risk of suicide

Mental illness is associated with an increased risk of suicide. 

In 2017, the ABS released data relating to other health conditions that people were experiencing when they died by suicide (known as ‘suicide comorbidities’) or had suicidal thoughts. Eighty per cent of suicide deaths were reported as having comorbidities, and a significant proportion of these were related to mental health.

The following mental health conditions were found to be commonly comorbid with (present at the same time as) suicide and suicidal thoughts:

  • mood disorders (including depression) – comorbid with 44% of all suicides
  • mental and behavioural disorders due to psychoactive drug use – 29.4%
  • anxiety and stress-related disorders –17.6 %
  • schizophrenia and delusional disorders – 6.5%
  • unspecified mental disorders – 5%
  • personality disorders – 2.8%
  • behavioural disorders usually occurring in childhood and adolescence – 1%.

Read more about suicide and mental illness.

Where to get help


More information

Mental health services topics

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This page has been produced in consultation with and approved by: SANE Australia

Last updated: October 2019

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