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Mental illness

8-minute read

What is mental illness?

A mental illness is a health problem that affects people’s thoughts, mood, behaviour or the way they perceive the world around them. A mental illness causes distress and may affect the person’s ability to function at work, in relationships or in everyday tasks.

1 in every 5 Australians — about 4 million people — suffers from a mental illness in a given year, and almost half the population has suffered a mental disorder at some time in their life.

There are many different types of mental illness. The most common are depression, anxiety and substance use disorders.

Mental illnesses can range from mild disorders lasting only a few weeks through to severe illnesses that can be life-long and cause serious disability.

What are the symptoms of mental illness?

Each types of mental illness has a different set of symptoms. For example, extreme dieting may be a sign that someone has an eating disorder. Hearing voices could be a sign of psychosis. An ongoing feeling of hopelessness after childbirth could be a sign of postnatal depression. People with anxiety will have excessive worry or fears, and people with depression will have a lasting sadness or low mood.

Drastic changes in a person’s thoughts, moods or behaviour can be a sign they have a mental illness. Changes can be sudden or come on gradually over a long period. A person who usually copes well with life may start to have trouble functioning at work or in normal activities due to a mental illness.

Here are some signs of mental illness to look out for:

  • unusual or illogical thoughts
  • unreasonable anger or irritability
  • poor concentration and memory, not being able to follow a conversation
  • hearing voices that no one else can hear
  • increased or decreased sleep
  • increased or low appetite
  • lack of motivation
  • withdrawing from people
  • drug use
  • feelings that life is not worth living or more serious suicidal thoughts
  • becoming obsessed with a topic, like death or religion
  • not looking after personal hygiene or other responsibilities
  • not performing as well at school or work

The symptoms of mental illness can come and go throughout a person’s life. Refer to the specific topics on this site for more detailed information.

What causes mental illness?

Researchers are still trying to understand what causes mental illness. There is no one cause — it can happen due to a mix of factors including genetics, how your brain works, how you grew up, your environment, your social group, your culture and life experience.

Some examples of these factors include:

  • Genetic factors: having a close family member with a mental illness can increase the risk. However, just because one family member has a mental illness doesn't mean that others will.
  • Drug and alcohol abuse: illicit drug use can trigger a manic episode (bipolar disorder) or an episode of psychosis. Drugs such as cocaine, marijuana and amphetamines can cause paranoia.
  • Other biological factors: some medical conditions or hormonal changes.
  • Early life environment: negative childhood experiences such as abuse or neglect can increase the risk of some mental illnesses.
  • Trauma and stress: in adulthood, traumatic life events or ongoing stress such as social isolation, domestic violence, relationship breakdown, financial or work problems can increase the risk of mental illness. Traumatic experiences such as living in a war zone can increase the risk of post-traumatic stress disorder (PTSD).
  • Personality factors: some traits such as perfectionism or low self-esteem can increase the risk of depression or anxiety.

When should I see my doctor?

Seeing a doctor is the first step to getting treated and returning to good mental health. If you’re concerned that you might be experiencing a mental illness, book an appointment with a doctor today.

How is mental illness diagnosed?

Mental illness can be diagnosed by talking to a doctor in detail about your symptoms. There are generally no blood tests or brain scans that can confirm a mental illness, although these tests may be useful in ruling out other possible causes of the symptoms.

Assessment will include questions about your thoughts, mood and behaviours. It may be helpful to bring along a family member or carer. Questionnaires are sometimes used, although a diagnosis should not be made on the basis of a questionnaire alone.

The symptoms of different mental illnesses are described in the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), published by the American Psychiatric Association. This manual is used by doctors to decide which mental illness you have.

It may be necessary to get a referral to a psychiatrist, psychologist or other specialised service for further assessment and treatment.

How is mental illness treated?

Mental illness is treatable, and most people with mental illness recover to live productive and happy lives.

The treatment is different for each type of mental illness and can vary according to the individual, the severity of the illness and past history of illness. The main types of treatment include:

If severe, or a person is at risk of suicide, then treatment may involve hospital assessment and maybe admission.

Can mental illness be prevented?

Good mental health can be boosted by positive things in life such as:

  • having support from family, friends and the community
  • having a strong sense of identity and culture
  • looking after your physical health by eating a healthy diet and exercising
  • reducing stress of possible
  • being optimistic
  • developing ways of coping with life’s problems
  • getting support

Complications of mental illness

Mental illness can attract stigma and discrimination, which can be 2 of the biggest problems for a person with these disorders. Up to 1 in 10 people with mental illness dies by suicide.

Resources and support

If you need help, talking to your doctor is a good place to start. If you’d like to find out more or talk to someone else, here are some organisations that can help:

  • SANE Australia (people living with a mental illness) — call 1800 18 7263.
  • Beyond Blue (anyone feeling depressed or anxious) — call 1300 22 4636 or chat online.
  • Black Dog Institute (people affected by mood disorders) — online help.
  • Lifeline (anyone having a personal crisis) — call 13 11 14 or chat online.
  • Suicide Call Back Service (anyone thinking about suicide) — call 1300 659 467.

Learn more here about the development and quality assurance of healthdirect content.

Last reviewed: November 2020


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