If you know five people, the chances are at least one is living with a mental health condition. More than 8.5 million Australians will need mental health treatment in their lifetime for depression, anxiety, substance use and or psychosis.

But why do these people die on average more than a decade earlier than people who don’t access mental health support?

People aged 15–74 who are treated for mental illness make up just over 22% of the total population. But they account for almost half (49.3%) of all premature deaths.

The vast majority die due to physical health issues – and they’re preventable.

Life expectancy has increased for others

Over the past 30 years, Australians overall have enjoyed a five to six year increase in life expectancy. This is largely due to improvements in health care and healthier behaviours, such as reductions in smoking and advances in early detection and treatment of cancer and heart disease.

However, people with mental illness have not enjoyed the same increases in life expectancy, leading to a widening gap.

This is true for a range of mental health conditions.

People with serious mental illnesses, such as psychosis, die on average 14 years earlier than the general population. Those with more common mental illnesses, such as depression and anxiety, also face a shorter life expectancy, dying 9–13 years earlier.

What are people with mental illness dying from?

Contrary to popular belief, the life expectancy gap among people with mental illness is not due to suicide.

Suicide makes up 1.6% of deaths, while the leading causes of early death are preventable physical conditions such as cancer, heart disease, respiratory disease and diabetes.

Our 2024 study used national data to analyse deaths from chronic diseases among people with mental illness. We found they were two to six times more likely to die prematurely than the rest of the population.

For example, people with mental illness are five to six times more likely to die from breast or prostate cancer than the rest of the population, and four times more likely to die from diabetes.

Overall, this leads to 16,658 preventable deaths for this population each year.

Why is this happening?

Many interconnected factors contribute to this health disparity. They include discrimination, socioeconomic disadvantage, access barriers, medication side effects, and the symptoms of the mental illness itself.

People with mental illness often face prejudice and discrimination, including from health-care workers, making them reluctant to seek care. When they raise health concerns, they may not be believed, are seen to be exaggerating, or their symptoms are dismissed.

This is known as diagnostic overshadowing. It means someone’s mental health condition “overshadows” their physical health and other concerns, and these are overlooked. This can mean serious health issues go undetected and untreated.

People with mental illness also face other challenges accessing preventative care and treatment. They are less likely to be vaccinated and much less likely to access screening and treatment for conditions such as cancer and heart disease, meaning diagnosis often happens at a more advanced stage, lowering survival rates.

This may be due to poor communication from health-care workers, stigmatising attitudes, and accessibility problems, such as not having access to transport.

When people are socially isolated, live regionally, or experience socioeconomic disadvantage, they may find it even harder to access care – and are even more likely to die early than others with a mental illness.

Medication side effects can also carry longer-term health risks, such as developing obesity from using antipsychotic medications.

What should change

Health care is a human right. For Australia to meet its commitments to the United Nations – and turn the tide on preventable deaths – we need to make sure people with mental illness enjoy the same quality of care as the rest of the population.

This means educating the health-care workforce about the dramatically higher risk of early death among people with mental illness, training staff how to recognise and respond to physical health concerns without stigma.

Integrating GPs with community mental health teams and including people with mental illness in designing policy and in health services is also key.

We need nationally funded programs for vaccination, smoking cessation and cancer screening that target people with mental illness. Regular monitoring and reporting can track progress and see whether these programs are working to close the life expectancy gap.

As a friend, family member, carer or health professional of someone with a mental illness, you can also help. For example, by asking when the person last had a physical health check-up, whether they have accessed cancer screenings and vaccinations, and if they need support.

Something simple – such as helping them make or attend an appointment – can make a big difference.

If this article has raised issues for you, or if you’re concerned about someone you know, call Lifeline on 13 11 14.