The more we learn about human psychology, the more it becomes apparent that physical and mental health do not exist in silos. The World Health Organization (WHO) defines health as “a state of complete mental, physical and social well-being and not merely the absence of disease or infirmity.”
Not only do our physical and mental health contribute to our overall sense of well-being, but they also impact one another. Poor mental health can deteriorate our physical health, just as chronic disease can increase our odds of suffering from mental health conditions.
Increasingly, mental healthcare providers are recognizing the interconnected state of our mental and physical health and looking at ways that treating mental health problems can improve our physical health (and vice-versa). In fact, in 2012, a paper published in The Personnel and Guidance Journal called physical health “an expanding horizon for counselors.”
In this article, we explore some of the many ways our mental health and physical health are related to one another, and how we can improve our mental and physical health alike by taking care of every aspect of our well-being.
How Mental Health Affects Physical Health
Poor mental health is associated with decreased longevity and increased rates of disease. Worldwide, it’s thought that people with mental illness die up to 20 years earlier than the general population, writes CNN. Suicide contributes to 17 percent of unnatural deaths, but researchers have actually found that people with mental illness are more likely to die young due to poor physical health, which is largely preventable.
Chronic stress, experienced by many people with mental illness, has long been associated with higher rates of cardiovascular disease and heart attack. Stress can increase blood pressure, alter heart rate and lead to changes in the vasculature and blood clotting that increase the risk of heart disease.
Mental illness has also been associated with increased odds of heart disease independently of chronic stress. For example, depression has been linked to a 67 percent increase in the risk of cardiovascular disease, while schizophrenia has been linked to a 50 percent higher risk.
One reason researchers surmise this may be the case is that people with mental illness may be less likely to receive preventative healthcare, such as blood pressure screenings. Some mental health medications may also affect the heart, though research asserts that these medications still do more good than harm in patients with mental illness.
Chronic stress also negatively impacts the gastrointestinal tract by accelerating the inflammation process and by affecting intestinal permeability and absorption of nutrients. Stress also affects appetite, though good nutrition patterns have an important protective effect against the stress response.
When it comes to mental illness, the gut-brain axis may be partially responsible for the strong linkage between mental health and digestive health. The gut microbiota — a collection of “good” bacteria that inhabit the gut and contribute to good digestion — have an important effect on mental health, as the gut produces hormones like serotonin that help maintain a positive mood.
If these healthy bacteria become imbalanced due to antibiotic use, inflammation or disease, the resulting effect could be mental illness. Preliminary studies suggest that gut dysbiosis and inflammation are strongly linked to depression and anxiety. Researchers continue to investigate the link between gut health and mental illness.
Immune Function and Cancer
You may have heard that stress lowers immunity, preventing the body from being able to defend itself from various diseases. This is thought to occur because chronic stress modifies the secretion of hormones involved in the immune system. But did you know that severe stress could have even more serious consequences?
Over long periods of time, exposure to severe stress — such as that associated with many mental health conditions — can suppress the immune system to the extent that malignant tumors could develop. Stress decreases the activity of T-cells, which are the natural killers of malignancy, which may allow tumor cells to proliferate in the body.
Studies show that cancer is no more likely in those with mental illness than in the general population, but that psychiatric patients are 30 percent more likely to die from cancer when it develops. This may be due to an increased rate of metastases in cancer patients with mental illness, as well as impeded access to health services that could increase the odds of survival.
It was previously assumed that people who were obese had an addiction to food, suffered from anxiety or depression or were eating to compensate for stress or unfulfillment in their lives. Now, we know that most people with obesity do not qualify for a psychiatric diagnosis, though there is still a strong relationship between obesity and mental health.
A study of over 9,000 U.S. adults found that obesity is linked with a 25 percent increase in the odds of mood disorders and depression, with a stronger link in women than in men. In overweight adults, those with depression are more likely to develop metabolic syndrome, a cluster of conditions that, occurring together, increase a person’s risk of heart disease, stroke and type 2 diabetes.
The reasons why obesity and mental illness are so intricately linked are unclear, but researchers have made many educated guesses on the topic. One hypothesis suggests that people who are depressed are more likely to seek out “comfort foods,” which are higher in calories, sugar and fat than the average diet. Likewise, lethargy and overeating are two symptoms of depression that may contribute to the likelihood of obesity. For example, a lack of energy due to depression may prevent a person from participating in aerobic exercise, which could otherwise help them moderate their weight.
How Physical Health Affects Mental Health
Just as mental health impacts physical health, so does our physical health impact our mental health. People with medical illnesses are more likely to suffer from depression, especially among those with chronic illnesses like cancer, dementia, HIV/AIDS and autoimmune diseases. Those who suffer from both depression and medical illness are more likely to experience more severe symptoms of both conditions. They may have more difficulty adapting to their medical illness and higher medical costs than those who do not have depression. But chronic illness is not the only way our physical health impacts our mental health. Nutrition, exercise and sleep all have an effect on our mental health as well.
Can what you eat affect your mental health? Absolutely! According to the American Psychological Association (APA), Western-style dietary patterns — high in fat, sugar and calories, and low in fruit, vegetables, whole grains in fiber — are correlated with reduced hippocampi volume in older adults, increasing the risk of cognitive decline. Another study of children found that the more vegetables, fruit and fatty fish the research participants ate, the fewer symptoms of ADHD they experienced.
There is strong evidence that certain nutrition patterns — such as the Mediterranean diet, DASH diet and MIND diet — can improve cognitive function. This becomes especially important as we age, when dementia and depression become more common.
All of these diets can be considered plant-based, in that they emphasize fruit, vegetables, whole grains, nuts, seeds and oils over meat and dairy products. Plant-based eating patterns are associated with lower levels of free radicals, chemicals associated with cognitive decline when left unchecked.
As Michael Otto, Ph.D., a Boston University psychology professor, told the APA, “People know that exercise helps physical outcomes. There is much less awareness of [how exercise impacts] mental health outcomes.” We know that exercise and mood are interconnected, but what we don’t understand is whether exercise actually improves mood or whether people simply move less when they are depressed.
We are still understanding how exercise impacts our mental health, but there is evidence that exercise lessens anxiety, improves mood and enhances overall mental health. A May 2019 study conducted at Harvard University discovered a 26 percent decrease in the odds of becoming depressed with each major increase in physical activity among research participants.
The study tracked all types of movement using a digital fitness tracker, showing that you do not need to run a marathon or do hours of CrossFit to reap the benefits of movement on mental health. To prevent depression, Harvard researchers say that just 15 minutes of high-intensity exercise (like running or lifting weights) or one hour of low-intensity exercise (like walking or housework) each day is sufficient.
Sleep problems impact just 10 to 18 percent of adults in the general population, but 50 to 80 percent of adults in a typical psychology practice. Traditionally, sleep problems have been treated as symptoms of mental illness, but some studies in children and adults suggest they may actually be a cause. For example, compared with normal sleepers, a 1989 study found that people who reported insomnia were found to be four times as likely to develop major depression within the next three years.
Sleep hygiene is especially important for people with mental health concerns. Lack of sleep can trigger an episode of mania in people with bipolar disorder, while sleep abnormalities may signify the advent of an episode of psychosis for those with schizophrenia.
Good sleep hygiene refers to a variety of practices used to improve nighttime sleep quality and daytime alertness. Activities like avoiding caffeine before bedtime, exercising during the day, ensuring exposure to natural sunlight and maintaining a comfortable sleep environment can all help you get a good night’s sleep.
How Can You Improve Your Mental and Physical Health?
Whether you’re faced with mental or physical health challenges, evidence suggests that being proactive about your mental health will benefit you in the long run. Being proactive includes not just the health practices we discussed previously — such as good nutrition, exercise and sleep hygiene — but also recognizing when you could benefit from outside intervention from a mental health professional. Treating mental health conditions, whether with medications, therapy or a combination of the two, is known to reduce the risks associated with them.