Dual diagnosis means someone has both a mental illness and a substance use problem. Many people with alcohol and drug problems have a range of mental health problems at higher rates than the general community. This includes increased instances of anxiety and depression. The abused substance could be tobacco, prescribed medication, illegal drugs or alcohol.

In many cases, it is hard to tell which problem came first. Perhaps the mental illness prompted the person to abuse drugs, or else their drug problem pre-dated their mental illness. The substance use could also worsen the symptoms of the person’s mental illness – for example, smoking marijuana can trigger a psychotic episode in some people.

A recognised problem is that many services for substance abuse and mental illness don’t overlap, which means that the person with dual diagnosis is managed through separate systems. This can make diagnosis and treatment more difficult. Victoria’s specialist mental health and drug and alcohol services are now working together, developing partnerships for the provision of integrated treatment and care of people with dual diagnoses.

A major issue

The realisation that mental illness and substance abuse can be linked is quite recent, so research is scant. Estimates on the scale of dual diagnosis in Australia vary, but include:
  • About 25 per cent of people with anxiety disorders, affective disorders and substance use disorders also have another mental disorder.
  • Around 64 per cent of psychiatric in-patients may have a current or previous drug use problem.
  • Around 75 per cent of people with alcohol and substance use problems may have a mental illness.
  • About 90 per cent of males with schizophrenia may have a substance use problem.

Integrated treatment can be difficult

Effective management of either substance use disorders or mental health disorders is challenging. Dual diagnosis can mean an increase in challenging behaviours including self-harm and aggression, avoidance of services, and resistance to or non-compliance with treatment and recovery programs.

Research suggests that people with a dual diagnosis respond well to integrated programs that address both their mental illness and their substance abuse. However, these programs were uncommon until recent years. Some of the reasons for this include:
  • Diagnosis can be difficult, because it isn’t always clear which problem has the more severe symptoms. Health services are now becoming more able to recognise dual diagnosis.
  • Mental health services are usually reserved for people with severe problems, so dual diagnosis clients with less severe mental health problems may not get treatment. They should, however, be referred to a suitable service.
  • A person with a mental illness may receive treatment, but their drug use problem could be dismissed as a minor side effect of their illness.
  • The number of workers trained in dual diagnosis treatment is slowly increasing. The services for mental health and substance abuse generally don’t overlap, so professionals in one field aren’t knowledgeable about the issues in the other field. It is hard to find professionals who are skilled in treating both substance abuse and mental illness.

Dual diagnosis treatment has improved in Victoria

Victoria has developed an effective way for the various health services to work together to help people with a dual diagnosis. This statewide approach means that mental health and alcohol and drug clinicians can contact the dual diagnosis teams for their area if they need support when treating a person with a dual diagnosis.

Common characteristics

According to experts in the field, a typical person with dual diagnosis is likely to have the following characteristics and experiences:
  • May be alienated and lack support from family and friends
  • Won’t cooperate with their health care providers
  • Is very emotional
  • Is likely to have severe psychiatric symptoms
  • May be homeless or moving frequently from one place of residence to another
  • Is likely to relapse
  • May be hospitalised or taken to accident and emergency departments reasonably often.

Issues for people with dual diagnosis and their families

The lack of professional knowledge about dual diagnosis can be frustrating for those affected and their families. Common experiences may include:
  • Health care providers may blame the client for being difficult and unresponsive to treatment, rather than questioning whether the health care system is failing to provide effective treatments and support for people with dual diagnoses.
  • If a dual diagnosis client first seeks treatment for drug abuse, the drug and alcohol workers may consider their mental illness as a secondary issue or side effect. Similarly, if they first seek treatment for their mental illness, then the mental health professionals may also consider their drug abuse as a secondary issue or side effect. The two problems are often not seen as interdependent and equally important.
  • Specialist and early intervention treatments are often not available.
  • Health care professionals may not involve the family in treatment, even though the family is frequently much more familiar with the problems and experiences of the person with dual diagnosis.

The future of treatment

Alcohol and drug services and mental health services are developing ways in which to respond to people with a dual diagnosis. Integrated service delivery and collaborative treatment is becoming core business for most services.

The Department of Human Services, Area Mental Health Services, alcohol and drug services and organisations such as the Alcohol and other Drugs Council of Australia, SANE Australia and the Mental Health Council of Australia continue to work together to make dual diagnosis a health care priority.

Where to get help

Things to remember

  • A person with dual diagnosis is someone who has both a mental illness and a substance use problem.
  • In many cases, it is hard to tell which problem came first; perhaps the mental illness prompted the person to abuse drugs, or else their drug problem pre-dated their mental illness.

More information

Mental illness

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Types of mental illness

Eating disorders

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

Last updated: January 2015

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