The Surprising Link Between Mental Illness and Physical Health

Research has shown that what goes on inside our heads can profoundly influence our body’s typical functions. A new study conducted by a team of researchers from Australia suggests that mental illness might manifest in the body even more obviously than it does in the brain. The study finds that poor physical health scores could be a better indicator of mental illness than changes detected on brain scans.

Lead author, psychiatrist, and neuroscientist Ye Ella Tian explains that those diagnosed with a mental illness showed subtle brain changes as you might expect, but they also had “considerably poorer physical health across multiple body systems compared to their healthy peers.” Research shows that mental illness is associated with poor physical health and chronic illness, such as obesity and diabetes, which may be related to the side effects of medication or disparities in access to healthcare.

To make matters worse, physical health more generally has been “underestimated, inadequately treated, and often overlooked in psychiatry” for decades, the University of Melbourne’s Tian and colleagues write. The impact of severe mental health conditions on other aspects of physical health, such as lung health, liver dysfunction, and bone loss, is less well-studied.

The team produced scores of brain health and the function of seven body systems, including the immune system, liver (hepatic) function, heart, lung, and kidney health. This allowed them to compare health scores among people diagnosed with mental illness to populations of people the same age. Differences in brain imaging results could accurately differentiate between the four mental health conditions studied: schizophrenia, bipolar, depression, and generalized anxiety disorder.

Despite the neural basis of mental illness, the study found that individuals with one or more of these disorders could be differentiated “with modest accuracy” from healthy controls of a similar age based on body health alone. Body health scores for liver and kidney function, the immune system, and metabolism were consistently poor across mental health conditions compared to healthy controls – and turned out to be better predictors of a mental health diagnosis than brain imaging scores.

Physical health measures would surpass differences in brain imaging results “was quite a surprising finding” given how mental illness is rooted in the disordered brain, University of Melbourne neuroscientist Andrew Zalesky explained in a podcast.

There are many possible reasons that explain why poor physical health goes hand in hand with mental severe illness: from the side effects of antipsychotic medications and mood-stabilizing drugs, to the chronic stress, increased infections, and enhanced immune responses that people with mental ill-health experience. The researchers note that their findings – which are mostly from white, British populations – aren’t meant to be used as a diagnostic tool.

Instead, the findings should help psychiatrists to appreciate how different aspects of physical health are affected by mental illness, and encourage them to treat both the body and the mind when managing people with mental health conditions. In this particular study, chronic physical health issues were often not diagnosed in people with mental health conditions, but the findings suggest “that poor body health and function may be important illness manifestations that require ongoing treatment in patients,” the researchers conclude.

The study conducted by the team of researchers from Australia finds that poor physical health scores could be a better indicator of mental illness than changes detected on brain scans. Although mental illness is rooted in the disordered brain, the study found that individuals with one or more of these disorders could be differentiated “with modest accuracy” from healthy controls of a similar age based on body health alone. Therefore, the study suggests that poor body health and function may be important illness manifestations that require ongoing treatment in patients.