The NeuroCAM of Immunity

What's your brain got to do with your immune system? A lot actually. While we all brace for challenging times amidst a pandemic, learn about how your brain can boost your immune system beyond social distancing. 

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Branch Out is all about the brain. Hence why we fund NeuroCAM research. But the brain doesn't work in isolation; it communicates with the rest of our body to help keep all of our other organs functioning properly. The immune system is no exception, and in fact, has a special relationship with the brain that scientists like to call psychoneuroimmunology. In case you have Hippopotomonstroses-quippedaliophobia, let's skip the jargon and go straight to learning about how neurons and white blood cells can influence each other. 

Just like a romantic relationship between two people, the health of a relationship between the brain and the immune system is dependent upon stress, so its important to understand the evolutionary function of our stress response system. Back when humans were hunters on the African Savannah, we were not the fastest or strongest predators. Like all other mammals, we could engage our sympathetic nervous system to provide us with bursts of energy that could mean the difference between life or death when trying to flee from lions. What set humans apart, however, was our ability to prolong these bursts of energy for extended periods of time through our stress hormones. As you might guess, when running away from lions or chasing down gazelles, the human body has different priorities than when chilling around the fire telling stories and our stress hormones are what allow us to make that metabolic shift on our body's needs. Digesting food isn't really that important if we might become food, so our gastrointestinal system shuts down under acute stress to give that energy instead to our muscles, heart, lungs, and immune system. You read that right! When faced with a stressor, our immune system naturally gets a boost, because how much would it suck if we successfully chased down a gazelle for food, only to die from infection when we cut ourselves in the chase? So under acute stress our body actually boosts our immune system...which is exactly the thing you want to do during the middle of a pandemic. 

Main Points

 

Our brain is interconnected with our immune system, so boosting one helps the other. 

Stress hormones are the middle man in this relationship, with acute stress actually boosting immunity. 

Chronic stress is detrimental to our immune systems.

Our body's stress response system was not designed to be turned on indefinitely, however. Eventually, one would catch the gazelle, or the lion would catch us. Unfortunately, our modern stressors don't fade quite so quickly, often lasting days or even weeks before we feel as though they are resolved. It is in this chronic stress state that our immune system goes haywire. When our brain is demanding that stress hormones be continuously pumped into our body, it enters a state of exhaustion. For our immune system, the initial boost to fighting off infections goes away as it also enters a state of exhaustion and actually looses its ability to properly fight off pathogens (like a certain contagious virus). Just like many a marriage, chronic stress can destroy the health relationship between our brain and our immune system. 

The marriage between neurons and white blood cells doesn't have to have a sad ending however. There are several things we can do to (even in quarantine) to restore some harmony. 

1. Exercise. As you now know, our stress response system was meant to be turned on in bursts. One highly effective way to break the cycle of chronic stress is to add those bursts back into your life in the form of exercise. When you go for a run, you do put more stress hormones into your body, but you are also going to end your run and shut them off. Regular exercise is literally teaching your body to more effectively put the breaks on your stress 1, which will mitigate the negative effects of the stressors in your life that won't go away. As a bonus, you are getting that acute boost to your immune system 2, just in case there was a lapse in your social distancing. 

2. Be Kind. Now that you know how bad chronic stress is for your immune system, why on Earth would you want to be a source of stress for other people? If we all practice a little bit of kindness to each other, the effect will ripple through out our communities and our collective immunity will be boosted. This can be as simple as giving someone else a roll of toilet paper now that it's as scarce as gold, or paying a compliment to the new stay-at-home Mom who clearly has bags under her eyes (from a distance of 6 feet!). 

3. Go Outside. There is an emerging field of research showing that exposure to natural environments has amazing stress-reducing effects 3. So much so that living by green spaces is associated with reductions in chronic health conditions usually exacerbated by stress 4. Rather than re-watching Friends, do your white blood cells a favour and go to your local park for a walk. 

4. All of the above. These tips will have the biggest immune boosting effect if they are practiced together, along with other aspects of a healthy lifestyle. While running on a treadmill will give you an acute boost in immunity, why not boost it even more by going for a run in the park? Make a point to smile at every person you pass along the way and you will really be helping mend your brain's relationship with white blood cells. 

5. Maintain your Mental Health. While this blog post focused on how your brain can compromise your immune system via the stress response, the immune system can also have negative impacts on your brain through chronic inflammation, with your mental health caught in the middle. This is where psychology comes into the psychoneuroimmunology, and this topic deserves its own blog post, so stay tuned! 

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Ty the NeuroGuy

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...about how placebo effects are related to the immune system

...about how the importance of exercise for our brain and body

...about social spreading of stress

 

Inspired By...

1. Stranahan, A. M., Lee, K., & Mattson, M. P. (2008). Central mechanisms of HPA axis regulation by voluntary exercise. Neuromolecular medicine10(2), 118-127.

2. Pedersen, B. K., & Hoffman-Goetz, L. (2000). Exercise and the immune system: regulation, integration, and adaptation. Physiological reviews80(3), 1055-1081.

3. Kondo, M. C., Jacoby, S. F., & South, E. C. (2018). Does spending time outdoors reduce stress? A review of real-time stress response to outdoor environments. Health & place51, 136-150.

4. Twohig-Bennett, C., & Jones, A. (2018). The health benefits of the great outdoors: A systematic review and meta-analysis of greenspace exposure and health outcomes. Environmental research166, 628-637.