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It's Not All In Your Head: The Physical Health Effects of Mental Illness

Once confined to the world of taboo topics, mental health and mental illness have become more widely discussed in recent years. The stigma surrounding these topics continues to be a large part of the conversation. After all, "it's just in your head." The stigma creates a stark contrast in how we treat physical health compared to mental health; however, the presence of physical health effects to poor mental health or mental illness can directly disprove this.

Physical Health vs. Mental Health: Stigma In Society (Mellow Doodles).

Mental illness is normally agreed upon to be a problem of the brain. The brain is an organ. Organs are a part of our body. And physical health is defined by the well-being of our body. However, this is often still not enough for mental illness to be taken seriously. Mental illness doesn't show up over an X-Ray like all other physical health symptoms that are visible or imageable. The symptoms of mental illness are often subtle and go undetected but can be just as damaging as a concussion or antibiotic-resistant infection.

Brain scans are typically used to assess trauma injuries or cancer detection, but what if we could also scan for mental illness? It turns out we sort of can. Our brain works using special cells called neurons that send and receive electrical signals throughout our body to function. These nerve cells use chemicals called neurotransmitters to communicate and tell our bodies how to feel or act. Dopamine and serotonin are some of these neurotransmitters and are often referred to as the "feel-good chemicals". Research has shown that people with mental illnesses such as depression have abnormal chemical balances in the brain, resulting in less "feel-good" neurotransmitters being released. Antidepressants often target the balance of neurotransmitters to improve the symptoms of depression, and the fact that antidepressants are effective proves the presence of a physical problem in the brain.

PET scan of the brain for depression (left) and healthy (right) showing brain activity

(Mayo Clinic).

In addition to effects on our brain chemistry, mental illness takes a toll on other areas of our body. High-stress levels often characterize mental illnesses such as anxiety. Every person experiences varying levels of stress, and some stress is even good for our bodies, but there are adverse health effects when this level gets too high for a prolonged amount of time. When we get stressed, our "fight or flight" response releases stress hormones, adrenaline and cortisol. Our body focuses on essential functions, which is why we see an increase in blood pressure and heart rate while the digestive system is suppressed. This is a normal and healthy response to stress that often provides us with the energy and motivation to complete tasks.

But when this healthy response to stress doesn't bring our bodies back to our resting state, our body will function in constant "fight or flight" mode and cause physical symptoms from a mental health issue. The suppressed digestive system can be behind appetite changes, digestive issues or stomach pain. The increased heart rate and blood pressure can set people up for potential cardiac issues in the future as the prolonged overwork of a heart can weaken heart muscles leading to coronary disease or even heart failure. Cortisol, one of the stress hormones released when we're feeling anxious, negatively affects our immune system, leading us to be more vulnerable to infection and disease and potentially decrease vaccines' effectiveness. Not only do we become more likely to get sick, but high levels of cortisol can also lead to tumour developments and lower white blood cell counts.

More concrete physical health diagnoses have also been connected to mental illness. Disorders such as depression and schizophrenia have shown a strong correlation with diabetes. This again links to the higher levels of cortisol, which can suppress insulin production as an attempt to use available glucose and prevent it from being stored. In a study done by the Canadian Mental Health Association, 9.3% of type 2 diabetics in Ontario were found to have been suffering from a mental illness. In the same study, 9.8% of people with health diseases, 10.1% of people with cancer, 10.9% of people with arthritis, and 11.4% of people with asthma suffered from mood disorders.

Comparison of mood disorder rates in Ontarians with and without chronic physical conditions (T. Gadalla)

However, it is important to note that mental illness can also be a symptom or result of physical illness. The mental strain of physical symptoms and stress of managing a physical illness can also lead to mental disorders, creating a paradox of health issues. Especially with people suffering from terminal illnesses, the stress and anxiety of nearing mortality are often enough for a mental illness diagnosis.

Much of the conversation on mental illness up to this point has been about relevance in today's society. However, the proven health effects should be enough to steer the discussion to more productive and meaningful topics. The rising mental health issues in today's youth due to a lack of advocacy and support for mental health are incredibly important and warrants deeper discussions and much more attention. The first step to joining the fight against mental illness is to do the work to educate ourselves and apply it to the people around us.


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Malla, A., Joober, R., & Garcia, A. (2015). "Mental illness is like any other medical illness": a critical examination of the statement and its impact on patient care and society. Journal of psychiatry & neuroscience : JPN, 40(3), 147–150.

PET scan of the brain for depression. (n.d.). Retrieved January 20, 2021, from

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Article author: Kerry Yang

Article editors: Sherilyn Wen, Edie Whittington


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