October 4, 2021

Understanding dual diagnosis

Man looks out to ocean

If a friend or family member has been diagnosed with a dual diagnosis it can be difficult to know what you can do to help and what treatment and support are available.

We’ve put together some useful information about dual diagnosis – what it is, how common it is, specialist services available for treatment and recovery, and practical tips to help you support the person you care about.

What is dual diagnosis?

Dual diagnosis is when someone has a mental health issue and an alcohol or drug use issue at the same time.

Mental illness and substance use affect people from all walks of life and all age groups, and dual diagnoses are common.

Around 50% of people experiencing a mental illness also have a substance use problem and vice versa.1, 2

What’s the link between mental health and substance use?

The links between mental illness and substance use are complex.

People with a mental health issue may use alcohol and other drugs for the same reason that other people use them – to relax or feel good.

Sometimes, the mental illness comes first and the substance use begins as a way to self-medicate or cope.3

At other times, substance use and mental health issues start at the same time and stem from a common cause such as trauma, stress or genetics.

Substance use can also change the chemical balance in the brain, causing mental health issues or making an existing mental illness worse.4

The challenges of dual diagnosis

While mental illness and substance use have their own independent challenges, there can be additional issues when they occur together, such as:

  • difficulty pinpointing whether specific issues came from substance use, mental illness, or both
  • a domino effect of relapse, where a step back in one treatment may cause a step back in both
  • adverse interactions with routinely prescribed medication for a mental health issue and the alcohol or other drugs being used
  • difficulty dealing with two disorders simultaneously. Some people may distance themselves from people close to them, reducing their support network without intending to.
  • double the stigma.5

People's experience of dual diagnosis varies.

It depends on the type of mental health problem and its symptoms, the drugs or alcohol used, and how these combine.

It also depends on the treatment or support the person receives. Some types of treatment may work for some people but not others.1

Treating dual diagnosis

People with dual diagnosis disorders are not a homogeneous group. The signs and symptoms can vary depending on the combination of disorders, the severity and the individual treatment needs.6

Mental health and alcohol and drug services have strengthened their understanding of the relationship between mental health and substance use and are increasing the provision of specialist services that understand and support the needs of people experiencing dual diagnosis.5

The best treatment for dual diagnosis is an integrated approach, where both the mental health issue and the substance use issue are treated simultaneously, and by the same treatment provider or team.7

Treatment for a mental illness may include individual or group counselling, meditation, peer support and lifestyle changes (e.g. exercise, healthy eating, quality sleep).

Treatment for substance use may include detox, managing withdrawal symptoms, counselling and behavioural therapy.

Supporting your loved one

There are many ways you can support someone you care about who is experiencing dual diagnosis.

  • Learn. Arming yourself with information about the symptoms and treatment options for dual diagnosis will help you understand your loved one and what they are going through.
  • Be available. You can be a shoulder to lean on and a willing ear for your friend or family member. Let your loved one know you are there to encourage them and be involved in their treatment if they want you to be.
  • Be patient. Recovery takes time, commitment and courage, and is an ongoing process. Relapse is a possibility and is a normal part of the recovery journey. Remember, people with dual diagnosis can and do recover.
  • Encourage help seeking. There are great supports available for both your loved one and you, some of which are outlined below.
  • Look after yourself. Make sure you are getting the emotional support you need. To take care of others you also need to take care of yourself and be realistic about the amount of care you’re able to provide. There are a range of support groups and hotlines also available for carers. 

What support is available?

Information and assistance are available for family, friends and people experiencing dual diagnosis.

Speak with your local GP or community health centre to find dual diagnosis services in your area or you can call:

  • The National Alcohol and Other Drug Hotline1800 250 015

The national hotline will transfer you to the Alcohol Drug and Information Service in your state, which can provide support, counselling, information and referrals for people experiencing alcohol and other drug issues (including dual diagnosis), their family and friends. 

Support, counselling, information and referrals for people experiencing mental health issues, family and friends.

24-hour hotline for carers to receive support, find resources and learn coping skills.

Support and information services for carers.

  1. Ross S, Peselow E. Co-occurring psychotic and addictive disorders: neurobiology and diagnosis. Clin Neuropharmacol. 2012;35(5):235-43.
  2. Kelly TM, Daley DC. Integrated treatment of substance use and psychiatric disorders. Soc Work Public Health. 2013;28(3-4):388-406.
  3. Harris KM, Edlund MJ. Self-medication of mental health problems: new evidence from a national survey. Health Serv Res. 2005;40(1):117-34.
  4. National Institute of Drug Abuse (NIDA). Why is there comorbidity between substance use disorders and mental illnesses?  [Accessed 6th June 2021].
  5. Health VIC. Dual Diagnosis Melbourne: Victoria State Government;  [Accessed 6th June, 2021].
  6. Mental Health Senate Committee. Dual diagnosis 'The expectation not the exception' [Accessed 7th July, 2021].
  7. American Addiction Center.Co-Occurring Disorder and Dual Diagnosis Treatment Guide  [Accessed 17 July, 2021].

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