People with severe mental illness die up to 20 years earlier than those without — a gap researchers say is only getting worse.

Key points: People living with mental illness face considerable physical health challenges

People living with mental illness face considerable physical health challenges Poor mental health increases risk of cardiovascular disease, diabetes and obesity

Poor mental health increases risk of cardiovascular disease, diabetes and obesity Lifestyle risk factors, psychiatric medications, and lack of physical healthcare are major issues

A new global report led by Australian researchers has revealed how a barrage of physical health challenges experienced by people with mental illness is contributing to years of lost life.

While it's been recognised for some time that people with severe mental disorders are more likely to die earlier, the researchers found those with mental illness were also more likely to be living with obesity, diabetes and cardiovascular disease.

"We see elevated rates of cardiovascular and metabolic diseases in people with depression, anxiety, schizophrenia, and even alcohol … disorders," said Joseph Firth, lead author and senior research fellow at Western Sydney University.

"Basically, all types of … mental disorders are associated with a double or even three-fold risk of these diseases."

This was related to a host of lifestyle risk factors such as sedentary behaviour, side effects of psychiatric medications, and a lack of adequate physical healthcare, the researchers said.

"It's not only a gap in life expectancy — it's also a massive gap in terms of quality of life," Dr Firth said.

The report, titled The Lancet Psychiatry Commission: a blueprint for protecting physical health in people with mental illness, recommends changes to health policy to ensure better integration of physical and mental healthcare.

"It really is a very severe problem," Dr Firth said.

"The extent of the gap in life expectancy between people with mental illness and the general population is actually increasing over time.

"Protecting the physical health of people with mental illness should be considered an international priority."

Lifestyle factors and sub-standard care

The report summarised the findings of almost 100 systematic reviews and meta-analyses on the prevalence of physical health problems among people with mental illness.

It found individuals with mental illness had a 1.4 to 2 times higher risk of developing obesity, diabetes, and cardiovascular disease compared with the general population.

"For patients with depression, the risk of developing cardiac disease, hypertension, stroke, diabetes, metabolic syndrome, or obesity is around 40 per cent higher than in the general population," the authors wrote.

The research showed all mental health diagnoses were associated with lifestyle risk factors including heavy alcohol consumption, smoking, sedentary behaviour, poor diet and poor sleep.

However, lifestyle factors were unlikely to be the only explanation driving poor physical health outcomes among people with mental illness.

The report also found differences in the availability and quality of healthcare were to blame, with some research suggesting people with mental illness were less likely to have physical examinations in primary care, and less likely to receive medical or surgical interventions.

"The issue here is about equality," said co-author Simon Rosenbaum, a research fellow at the University of New South Wales.

Dr Rosenbaum also said lifestyle interventions — such as encouraging people to be more active or eat healthier — were known to help reduce chronic disease in the general population and had to become a core component of mental healthcare.

"We must take what works and find innovative and cost-effective ways for making these interventions a standard part of care for those treated for mental illness."

But there were challenges to this approach.

"The general population find it difficult to engage in healthy lifestyles. There are a lot of barriers," Dr Rosenbaum said.

"When you compound that with living with a mental illness and the issues associated with that … it's actually very difficult for people to engage in these sorts of behaviours. They need adequate support, they need time."

For example, lifestyle interventions wouldn't always "cut it" with people on psychiatric medications that induce sedentary behaviour, make them feel lethargic, or increase food cravings, Dr Rosenbaum said.

"If we're serious about changing people's lifestyles, we need to take these things into account."

The report found some psychiatric medications could also play a direct role in causing disease.

"Antipsychotics and certain antidepressants can have quite severe metabolic side effects, which if left unaddressed, result in cardiovascular disease, cardio-metabolic diseases, and early death," Dr Rosenbaum said.

"So, improving evidence-based prescribing of psychiatric medication is very important."

Integrating physical and mental healthcare

Independent expert Max Abbott, a professor of psychology and public health at Auckland University of Technology, said the report's findings were no surprise.

"These high rates of physical health morbidity and greatly reduced life expectancy are totally unacceptable," he said.

In addition to lifestyle factors and medication side effects, he said stigma, discrimination, poverty, unemployment, housing problems and social isolation were "undoubtedly also important".

"Hopefully the Lancet report will help mobilise global efforts to address this too-long neglected issue," he said.

The report's authors recommended physical and mental health care should be better integrated.

They also recommended a multidisciplinary approach to mental health treatment that incorporated health professionals with expertise in nutrition, physical activity, and behaviour change.

"The evidence is very clear that having non-traditional services — exercise physiology, dietetics, allied health — should actually be a routine part of mental health treatment," Dr Rosenbaum said.

He said in Australia there is a system for doctors to refer people to see dietitians and exercise physiologists for lifestyle interventions.

"What's unfortunate is that it's entirely under-utilised. That's partly due to awareness and education, but it's also due to a lack of knowledge about where providers are."