We all know by now that stress is bad for our immune system. We’ve heard it a million times, especially since 2020. But did you ever wonder how, exactly, a feeling of unhappiness or worry can turn into swollen glands or a fever? How can something so intangible as a feeling cause such a physical reaction? Let’s take a closer look.
When our immune system becomes triggered by something (infection), our body responds in the following ways: fever, changes in liver metabolism, reduced food and water intake, and increased cortisol production. This immune response is triggered so that our body can preserve energy and we can fight the infection. Chemicals from the infection travel to the brain, and the brain triggers the body to produce this sick response. But what causes these chemicals in the brain to trigger an immune response?
- First, there are molecules called macrophages that are first on the scene when we get an infection somewhere in our bodies.
- These molecules (macrophages) make chemicals (let’s just called them cytokines to keep it simple). Cytokines travel through the blood and send signals to our brain.
- Guess what? When scientists block the receptors for these cytokines, animals show no sign of sickness after infection. And, when cytokines are introduced into the brain, even when there is no infection, the animal shows signs of sickness anyway. Pretty cool, right?
- Cytokines can’t get to the brain through the blood-brain barrier. Scientists found that we have receptors for these cytokines on our nerve cells, and when the cytokines bind to the nerve cell, it sends a signal to our brain. So, there is an actual PHYSICAL place on our cells where immune-system chemicals and nerve cells communicate.
- It’s a 2-way street. Now we know how infection triggers the brain to produce a “sickness” response on our bodies. Plus, communication goes both ways. When we experience stress, the same system in the brain sends a chemical signal to the body to produce a sickness response. That’s how stress literally makes you sick.
- Studies in humans have found that people getting treatment for cancer (which includes pumping lots of cytokines into the bodies) can end up with severe depression, and people with severe depression often have elevated cytokine levels in their bodies.
- Animal studies show that pumping cytokines into rats can result in memory problems.
Coping with stress, and therefore reducing the chemicals that our brain releases into our bodies when we are stressed, has a powerful effect on our health, digestion, and memory. If you are stressed/anxious/worried/sad/angry, and especially if you feel those negative emotions most of the day, more days than not, it’s extremely important that you find ways to reduce that stress because that stress is affecting your entire body.
Now is the time to act on all the advice you’ve been hearing about reducing stress: exercise, stay socially connected, get a good night’s sleep, meditate, or talk to a mental health professional. Dr. Ashley Gorman is a neuropsychologist specializing in adults. She has experience in comprehensive neuropsychological evaluations of a wide range of cognitive problems resulting from dementia, stroke, cerebrovascular disease, concussion/traumatic brain injury, psychiatric disorders, ADHD, learning disorders, and other medical conditions
