Substance Use Disorder & Mental Illness: What is the relationship?

Substance use disorder (SUD) and other mental illness are complex conditions that often intersect, creating significant challenges for those affected. Understanding the relationship between these two is crucial for effective treatment and support.

Mental illness and substance use disorder frequently co-occur and, when this happens, are generally referred to as dual diagnosis or comorbidity. Individuals with substance use disorder are more vulnerable to developing other mental health disorders, and vice versa. This bidirectional relationship can complicate diagnosis and treatment, as the presence of multiple mental health conditions can exacerbate each other’s symptoms and progression.

The relationship

It’s important to understand that substance use disorders are also classified as mental health disorders. According to NSMHW 2020–2022 one in 5 Australians (21.5%) had a mental disorder for a 12-month period. Of these 3.3% had a substance use disorder, 17.2% had an anxiety disorder, and 7.5% lived with an affective disorder. With some people having more than one disorder.

There are multiple factors that contribute to the relationship between SUD and other mental health disorders. Genetic predispositions, environmental influences, and neurobiological factors play significant roles. For instance, genetic vulnerabilities may increase the likelihood of developing both conditions. Additionally, trauma, stress, and adverse life experiences can contribute to the development of both substance abuse and other mental health disorders.

The use of alcohol and drugs may seem to temporarily alleviate symptoms of depression or anxiety, which can lead people to self-medicate. However, this relief is often short-lived and can ultimately exacerbate mental health symptoms and lead to addiction.


Effectively treating individuals with dual diagnosis requires a comprehensive and integrated approach that addresses both the substance use disorder and other mental health disorders simultaneously.

Integrated treatment programs, which combine mental health and substance abuse services, offer a more holistic approach to addressing dual diagnosis. These programs provide coordinated care that is tailored to an individual’s unique needs and include holistic therapy, medication management, psycho-education, and support groups.

For successful recovery, it’s important to address any underlying issues such as trauma, co-occurring medical conditions, and social determinants of health. Holistic interventions that focus on improving overall well-being enhance treatment outcomes and long-term recovery.

Supporting a loved one with substance use and other mental health disorders

It can be challenging to support a loved one who is struggling with both substance use and other mental health disorders. Taking the time to learn about your loved one’s specific issues and understanding their experiences, triggers, and challenges can help you provide effective support.

Recovery from dual diagnosis can be a long and difficult journey. Encourage your loved one to seek professional help and treatment, along with offering understanding and empathy. By creating a nurturing and supportive environment you can help to create a space for stability and emotional support during difficult times.

It’s also vital that you practise self-care. It can be emotionally draining to support someone with dual diagnosis. Make sure to prioritise your own well-being, by setting healthy boundaries, seeking support from others, and taking time for your own self and activities.

By offering consistent support, encouragement, and understanding, you can play a crucial role in helping your loved one navigate the challenges of dual diagnosis and work towards healing and recovery.