What is a severe and persistent mental illness?

Severe mental illness is characterised by a severe level of clinical symptoms and degree of disablement to social, personal, family and occupational functioning. An estimated 3.1% of the population have severe disorders, equivalent to 690,000 people. About one third of the severe group have a psychotic illness, primarily schizophrenia or bipolar disorder. The largest group (approximately 40%) is made of people with severely disabling forms of anxiety disorders and depression.

Severe mental illness is often described as comprising three sub categories:

  1. Severe episodic mental illness – refers to individuals who have discrete episodes of illness interspersed with periods of minimal symptoms and disability or even remission. This group comprises about two thirds of all adults who have a severe mental illness.
  2. Severe and persistent mental illness – refers to individuals with a severe mental illness where symptoms and/or associated disability continue at high levels without remission over long periods (years rather than months). This group represents about one third of all adults who have a severe mental illness.
  3. Severe and persistent illness with complex multiagency needs –the most disabling of the severe category requires significant clinical care (including hospitalisation), along with extensive support from multiple agencies to assist in managing most of the day to day living roles (e.g. housing support, personal support worker domiciliary visits, day program attendance). This group is relatively small (approx. 0.4% of adult population, 60,000 people) and is the group targeted for Tier 3 packages under the NDIS.

Department of Health and Ageing. Accessed here.


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