Research and data

Mental health and physical health cannot be separated

mental health and physical health are intrinsically tied together

In the seventeenth century, the French philosopher, Rene Descartes, put forth the notion of “mind/body dualism,” suggesting that the mind and body operate in fully separate spheres; one physiological and one spiritual. This idea has informed modern medical practices, at least in Western countries. But today, it has become clear that distinguishing between mind and body, while convenient, is impractical. In fact, the mind and body are deeply intertwined, and mental wellbeing is crucial for physical wellbeing.

People with mental illnesses are at increased risk of chronic diseases, such as heart disease and diabetes, and infectious diseases, too. For example, research has shown people with depression have worse prognoses following heart disease (like a heart attack or heart failure) and are also more likely to develop heart disease and/or diabetes for the first time. A recent review summarizing currently available data reported a 30-90% increase in risk of ischemic heart disease among persons with depression and between a 30-40% increase in risk of diabetes. Similar results have been found for posttraumatic stress disorder and other mental illnesses.

While it will take more research to know for sure, there is some evidence that mental and physical illnesses occur together — not just because these conditions share similar underlying risk factors, but because mental illnesses can actually lead to physical illness.

There are plausible ways poor mental health could lead to poor physical health

People with poor mental health may be less motivated to exercise, eat well, and/or take medications. They also may receive less support to make healthy lifestyle changes. There may even be biological changes that occur in response to mental illness that increase risk for chronic illnesses, such as changes to brain functioning, increased inflammation, and immune system changes that make it harder to fight infections.

The link between mental health and physical health is costly. A study on the economic cost of depression found that for every dollar spent on direct medical costs of treating depression, the U.S. incurred $4.70 USD in direct and indirect costs due to co-occurring medical conditions, making co-occurring medical conditions the costliest aspect of depression.

Employers should take note of mental health and physical health

Of the $4.70 USD mentioned above, just under half was in the form of lost workplace productivity. People with depression miss more days of work than people without depression – possibly due to a combination of depression and other conditions that mental illnesses can cause or exacerbate. Luckily, workplace-related policies such as allowing paid mental health days for employees, providing resources for mental and behavioral health support, and providing insurance coverage for mental health services can improve employee wellness and boost productivity.

Clinicians should take note of the links between mental health and physical health, too

The American Heart Association recently put out a scientific statement on the “mind-heart-body connection,” which highlighted strategies for cardiologists, such as incorporating short screening surveys to assess patients’ psychological health, speaking with patients about how psychological health might affect a current heart condition or risk for future heart conditions, and using team-based approaches to directly integrate mental health care into heart health regimens.

Mental health and physical health go hand in hand. Clinicians, employers, and others can help create healthier and more complete mind and body wellness. We ought not to focus on one aspect of health at a time, but rather, on all aspects, together.

Meghan Smith is a doctoral candidate in Epidemiology at the Boston University School of Public Health. Her research interests include the epidemiology of mental health and the social determinants of health. She is interested in how research findings are translated to real world change. Her work is informed by a global perspective, having worked in multiple countries including United States, Rwanda, and Oman.

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