From yogis to Eastern philosophers to integrative psychiatrists more recently, many have heralded the relationship between the mind and the body. In a previous article, we looked at the research on the connection between gut health and mental health. This time we’re looking at another link that has recently made the headlines: that between the immune system and mental health.

New research findings suggest that the two might be more intimately connected than previously thought. And a whole new psychiatric field called immunopsychiatry has emerged to explore this connection. Let’s explore the link and look at some actionable strategies to keep both systems happy.

Why is inflammation problematic?

As kids, we’ve all fallen over at some point and even injured ourselves. Luckily, the immune system allows the body to heal after an injury. But do you remember the nausea and heat that you felt after an injury? That was inflammation in action. Inflammation is our body's defence against attackers, be it pathogens or other foreign bodies. Our immune system releases antibodies and proteins, as well as blood flow to the damaged area. Not only has the immune system healed us from injury plenty of times, but it has also taught us to be more careful with our movements. Whilst inflammation can be incredibly beneficial, if prolonged over a longer period, it can increase the risk of developing mental health issues.

People with high levels of inflammation in their body are more likely to develop conditions like cardiovascular disease and type 2 diabetes. More recently, studies have shown that people with heart disease who have depression seem to have even more inflammatory responses in their bodies than those who don’t have depression. During the pandemic, researchers have also found an association between mental health problems and immune response, especially amongst the elderly.

What does the immune system have to do with mental health?

Your brain cells and immune cells are constantly communicating. This communication is possible thanks to messenger molecules called pro-inflammatory cytokines. These cells bridge the gap between the immune system and the brain, allowing the two to communicate with each other.

Now cytokines have very much been in the spotlight recently. Studies have found that when too many cytokines accumulate in your bloodstream, they break through the blood-brain barrier and make you feel ill. As we’ve seen earlier, that response is useful if you have an injury or are dealing with a pathogen. The cytokines are sending the message that you need to slow down and heal. But if those cytokines stay elevated, they can lead to mental health issues like depression.

Studies have found that people with depression (especially those who don’t respond to treatment with SSRIs) often have higher levels of cytokines in their systems. And when people are prescribed drugs that increase inflammation in the body, they’re at a higher risk of depression. But the relationship between the immune system and mental health goes both ways.

How does mental health affect your immune system?

Stress can weaken the immune system. When you're stressed, your body releases cortisol, a hormone that suppresses the immune system. Being exposed to chronic stress can leave you more susceptible to infection and illness. Additionally, people who are depressed or have anxiety disorders often have poor diets and don’t get enough sleep. All of these factors can hamper the immune system's ability to function correctly and do its job.

But just how directly linked are the brain and the immune system? Between 1982 and 1992, pioneer researchers Janice Kiecolt-Glaser and Ronald Glaser examined the immunity of medical students during their three-day exam period versus their immunity one month before exams. They found students’ immunity was reduced annually due to stress, and that those taking the exams had fewer natural killer cells, which fight tumours and viral infections.

These findings opened the floodgates of research, and by 2004, researchers at the University of British Columbia and the University of Kentucky had nearly 300 studies on stress and health to review. They found that for stress of any significant duration, whether a few days to a few months or years, all aspects of immunity went downhill.

The science is here. One study on mice suggests that stress can also change the way in which immune cells function. When exposed to repeated, unpredictable stress, their brain cells and immune cells started communicating with each other more, leading to inflammation and affecting their immune system.

What can you do to keep your mental health and immune system in check?

The relationship between inflammatory cytokines, the immune system, and mental health can become fruitful avenues for new treatments.

"The inflammatory model of mental health can help to understand some of the triggers of emotional distress. Combining physical and mental health in the therapy session can to develop psychological tools that one can use to achieve a good quality of life and a good life balance,"

says Dr Renata Fialho, clinical psychologists and researcher.

While the research is still ongoing, there are a few things that you can do to keep your mental health and immune system healthy.

1. Make sure that you eat a balanced diet and get enough sleep. Include foods that boost immunity and brain function in your diets, such as berries, leafy greens, and omega-three fatty acids. To get better sleep, try sticking to a set schedule, create a restful and relaxing room for sleeping, and try to limit daytime naps to 30 minutes a day.

2. Stay active and social. Exercise releases endorphins, which have mood-boosting effects. If you’re looking for something different, check out our article on cold water swimming, which is known to give your immune system a good boost. And if you’re going to go for that cold dip, maybe bring a friend or two along. Spending time with friends and family also helps reduce stress levels.

3. Finally, set time aside for relaxation and de-stressing. Practices like yoga and meditation can help you achieve this.

Looking to improve your overall health? We can help

Whether you are struggling mental or physical health, it's easy to see how your immune system can also take a hit. Keeping up with regular exercise, eating healthy foods that boost immunity and brain function, connecting meaningfully with people — all of these simple things will help keep both your mental and physical wellbeing at their best!

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