Physical health of people with mental illness

Key points

People living with mental illness, and in particular severe mental illness (SMI), are more likely to experience comorbidity of physical conditions, more likely to be hospitalised for potentially preventable reasons and tend to die earlier than the general population (Sara et al. 2021; Lawrence et al. 2013).

For more information on mental illness, see the Mental Health Online Report.

How common is physical illness among people with mental illness?

According to the 2020–2022 NSMHW, an estimated 4.3 million Australians aged 16–85 years, or 22% of this population, had experienced a mental disorder in the 12 months prior to the study. Of these, 2 in 5 (39%) also had a long-term physical health condition. This represents an estimated 1.7 million people or 1 in 12 (8.4%) adults experiencing both a mental illness and a long-term physical health condition (ABS 2023).

The 2021 Australian Census results – which include people of all ages – showed a notable overlap between physical health and mental health problems: people who reported having a mental illness were more likely to report having a long-term health condition (Figure PHYS.1) (ABS 2022). Among the most common long-term conditions reported by those with a mental illness were arthritis, asthma and diabetes (Figure PHYS.1). Furthermore, given that the Census relies on people self-reporting conditions, this is likely to be an underestimate as many people did not respond to this item or may not be aware that they have a long-term health condition. Refer to Chronic conditions and multimorbidity for more information.

Figure PHYS.1: Long-term health conditions reported by persons with and without mental illness in 2021

A recent study of Australian general practice records examined the prevalence of physical health conditions and biomedical risk factors among people with SMI. Similarly, it showed a notable overlap between mental and physical illness (Belcher et al. 2021). The prevalence of all surveyed biomedical risk factors was higher among patients with SMI than patients without. These included:

• dyslipidaemia (high cholesterol) (25% among those with SMI compared with 18% in patients without)
• hypertension (27% compared with 22%)
• obesity (29% compared with 19%).

The prevalence of all surveyed physical conditions was also higher among patients with SMI than patients without. These included:

• back pain (35% among those with SMI compared with 19% in patients without)
• cardiovascular disease (10% compared with 6.7%)
• gastro-oesophageal reflux disease (29% compared with 15%)
• arthritis (27% compared with 19%)
• cancer (19% compared with 15%).

Almost three-quarters (71%) of patients with SMI had at least one of the surveyed physical health conditions, compared with over half (54%) of people without.

The second national survey of People Living with Psychotic Illness also provided estimates on the physical health of Australians living with a psychotic illness (Morgan et al. 2012). Chronic back, neck or other pain was the most common chronic physical condition (32% compared with 28% for the general population) identified among people with a psychotic illness in 2010. Other common conditions included asthma (30% compared with 20% for the general population) and heart or circulatory conditions (27% compared with 16%).

In 2010, one-quarter (24%) of people with a psychotic illness were at high risk of cardiovascular disease, almost half (45%) were obese and almost two-fifths (38%) reported gaining weight as a medication side effect. Physical activity levels were markedly lower in people with a psychotic illness, with 96% classified as either sedentary or undertaking low levels of exercise in the previous week compared with 72% for the general population (Morgan et al. 2012).

Causes of physical illness among people with mental illness

Mental health is known to affect physical health. For example, there is a long-established association between depression and heart disease. Multiple studies across various types of populations have shown that people with depression but no history of heart disease when the depression is assessed are at markedly higher risk for coronary heart disease or cardiac mortality (Carney and Freedland 2003). Similarly, among patients who have just experienced a major cardiac event, such as a heart attack, those with depression are at an increased risk of another cardiac event or cardiac mortality compared to non-depressed patients (Dhar and Barton 2016). While the association between the depression and coronary heart disease is well known, researchers have only recently begun to understand the biological mechanisms behind this relationship (Dhar and Barton 2016). Yet the reasons people with mental illness and especially SMI are more likely to experience poorer physical health and reduced life expectancy compared to the general population go beyond the physiological changes associated with mental illness. 

According to the Royal Australian and New Zealand College of Psychiatrists, the reasons people living with severe mental illness experience poorer physical health include:

• greater exposure to the known risk factors for physical disease such as lower socio-economic status, smoking, poor nutrition, reduced physical activity and higher sedentary behaviour
• reduced access to and quality of health care due to financial barriers, and stigma and discrimination among health care providers
• systemic issues in health care delivery, especially the separation of mental and physical health services, and a lack of clarity about who is responsible for monitoring the physical health of people with serious mental illness
• adverse effects of psychotropic medication, in particular their contribution to metabolic syndrome, obesity, cardiovascular disease and type 2 diabetes
• impacts from polypharmacy (the prescription of multiple medications) and prescribing practices
• lack of capability among both generalist and specialist health care staff to deal with complex comorbidities – mental health staff may lack skills, training and confidence to treat physical conditions and vice versa for physical health teams (RANZCP 2015).

For some people living with mental illness, symptoms may interfere with receiving medical care or compromise effective communication of physical symptoms with health care workers (Melamed et al. 2019).

In addition to poorer physical health and shorter life expectancy, higher rates of physical comorbidity among people with SMI can lead to higher levels of ongoing disability, reduced participation in the workforce and a greater likelihood of poverty and welfare dependency (RANZCP 2015).

Life expectancy

That people living with mental illness have a reduced life expectancy compared with the general population has been extensively documented around the world (Chang et al. 2011; Walker et al. 2015; Plana-Ripoll et al. 2019). Research from Western Australia found that the gap in life expectancy for people with mental illness registered with West Australian mental health services compared with the general population in 2005 was 15.9 years for men and 12.0 years for women (Lawrence et al. 2013). This research also indicated that the mortality gap for people living with mental illness had increased from 1985, by 2.5 years for men and 1.6 years for women since 1985, with the increase largely driven by gains in life expectancy for the general population (Lawrence et al. 2013) . This finding aligns with studies from other high-income countries suggesting that the mortality gap for people with mental illness may be increasing over time, in part due to gains in life expectancy for the general population not experienced (or at least not experienced in equal measure) by those with mental illness and especially SMI (Neilsen et al 2013; Hayes et al 2017; Laursen et al 2019).

Rather than a direct result of mental illness or death by suicide, almost 80% of premature deaths of people with mental illness are due to potentially preventable physical health comorbidities (Lawrence et al. 2013). These include type 2 diabetes, respiratory diseases, cancer and cardiovascular disease (De Hert et al. 2009). Compared to the general population, people with SMI have a 2- to 3-fold risk of developing hypertension and metabolic syndrome and, if under the age of 50, a 3-fold risk of dying from coronary heart disease (De Hert et al. 2009; Osborn et al. 2007). If diagnosed with cancer, people living with SMI experience higher rates of mortality compared to the general population (Launders et al. 2022; Charlesworth et al. 2023).

Substance use and mental illness

Use of alcohol, tobacco and illicit drugs can trigger or worsen mental health issues and are strongly associated with physical health conditions including cancer, cirrhosis, and cardiovascular disease (AIHW 2022).

The relationship between mental illness and substance use is complex. A mental illness may make a person more likely to use drugs as an attempt to self-medicate symptoms associated with their mental illness. Conversely, substance use may be a contributing factor for the initial symptoms of mental illness. Certain substances may cause a substance-induced psychosis which can last for days or weeks after the end of intoxication. However, if someone has a pre-disposition to developing a psychotic illness, such as schizophrenia, the use of illicit drugs may bring on the first episode of what can be a longer-lasting psychotic illness (NDARC 2011). Critically, this does not mean that mental illness necessarily causes substance use and vice versa: common risk factors (such as trauma, personality traits, genetic influences and the childhood environment) may cause substance use and mental illness to independently develop in the same individual (UNODC 2022).

Among people living with mental illness, there are higher rates of alcohol, tobacco and other drug use compared with people without mental illness (refer to Figure PHYS.2).

Figure PHYS.2 Proportion of people aged 18 years and over who use alcohol, tobacco and illicit drugs by mental health status in 2019 

Comorbidity between substance use disorder – which itself is categorised as a mental disorder – and other kinds of mental disorders is common (Mills et al. 2019). According to the NSMHW 2020–2022, while 8.8% of people who met the diagnostic criteria for an anxiety or affective disorder also met the criteria for a substance use disorder, almost half (46%) of people who met the diagnostic criteria for substance use disorder also met the criteria for an anxiety or affective disorder (ABS 2023).

While mental illness is associated with a reduced life expectancy, research has shown that comorbid substance use disorder alongside other mental disorders is associated with markedly higher mortality rates and larger reductions in life expectancy (Plana-Ripoll et al. 2020).

For more information, refer to Alcohol, tobacco and other drug use among people with mental health conditions.

Impact of COVID-19 on people living with mental illness

A number of data sources have indicated impacts on both the mental and physical health of Australians during the pandemic. As in other parts of the world, the pandemic and related restrictions had significant impacts on the mental health of Australians. Multiple sources of data indicated increased and more widespread psychological distress compared with pre-pandemic levels and increased use of mental health services and mental health prescriptions (ABS 2021; Biddle and Gray 2021; Butterworth 2020; AIHW 2023). Those aged 18–35 years, women, people with a disability, renters, and people who report having a mental health condition were more likely to report high or very high levels of psychological distress (ABS 2021).

Despite modifications and additions to health service delivery models during the pandemic (for example, telehealth consultations), many people delayed access to health care which can lead to acute and long-term health consequences for individuals (White et al. 2021). Issues included restrictions on movement during lockdowns, fear of contracting COVID-19, fear of overburdening the health system, financial stress and disruptions to elective surgery and other health services. Notably, people experiencing high levels of psychological distress were 6 times more likely to choose not to consult a health professional when needed than those who were not (Zhang et al. 2020).

For people living with SMI – a group which generally has less access to health care – pandemic-related restrictions may have worsened physical health due to challenges particularly affecting this group (Melamed et al. 2020). People with SMI were already overrepresented in acute physical health care episodes in hospitals prior to the pandemic, therefore the burden placed on acute health care settings from the pandemic may have disproportionally affected this group (Melamed et al. 2020; Sara et al. 2021).

Future directions

Data linkage, for example through the National Integrated Health Services Information (NIHSI) data asset (also known as the National Health Data Hub), may provide further insights into the relationships between mental illness and physical comorbidities among the Australian population. While separate data collections provide a limited view on peoples’ overall health, data linkage between collections allows for analysis of the impact of mental illness on physical health conditions from across different service settings and types of service usage. This data could assist in identifying areas of disadvantage in broader health settings and barriers to service usage for people with mental illness, which is critical as this population group accesses health services at a lower rate than the general population.

Where can I find more information?

For more information on the physical health of people with mental illness, refer to:

• Equally Well Improving the physical health of people living with mental illness
• Victoria University Being equally well: A national policy roadmap to better physical health care and longer lives for people living with serious mental illness 
• The Royal Australian & New Zealand College of Psychiatrists Keeping body and mind together: improving the physical health and life expectancy of people with serious mental illness
• World Health Organization (WHO) Management of physical health conditions in adults with severe mental disorders, WHO Guidelines 

This section was last updated 14 February 2024