Depression: A Response to Chronic Inflammation
We’ve all been at the point where we have felt terrible, either physically or mentally. Sometimes, however, these sensations are so strong, motivation to get up and face the day is the last thing we feel capable of doing. Although it’s known that getting out of bed to simply move the body and eat something nutritious will make us better, it still feels impossible.
It is common knowledge that a person’s lifestyle can have a direct effect on their mental health; nobody would ever contest this claim… yet the conversation usually just stops there. We know that it is true, but if asked to explain how, we have little more to offer than something like, “Well, of course a healthy body would lead to a healthy mind.”
If we cannot truly understand a claim, however, can we truly believe it?
Personally, I’ve always “known” that eating healthy would make me feel better, but I’ve never really “felt” it. Eating junk food or having a beer fills us with pleasurable sensations: it tastes good, smells good, and if it’s booze, maybe it literally feels good. We have direct evidence of how these things make us feel, and it is instantly available. When was the last time you got a rush like this from a garden salad, with flavour so intense that it made you salivate so hard that it hurt? The opposite is true as well. While eating calorie-dense foods, we hardly think about how if we keep this up, our day-to-day mood will suffer. While eating whole, fibrous foods like veggies, we are rarely thinking, “This is going to keep me from feeling lethargic tomorrow!”
It is this separation of cognitively “knowing” something, and the very visceral and personal notion of “feeling” or “believing” that something is true, that makes it difficult for people to make lasting lifestyle changes to address or benefit their mental health. For myself, having a concrete link between the “knowing” and my personal experience helps to facilitate the “belief” part of the process. It was watching a video on the YouTube channel “What I’ve Learned” that helped to cement in my mind the idea that my day-to-day diet and activity levels directly impact the state of my mind. The video is titled, “What’s the point of Depression?”, and it does an amazing job of illustrating some of the biological mechanisms behind this.
As explained in the video, depression has been linked with a variety of genes that serve some sort of function within the immune system.  There are some theories that say it may be linked with the inflammatory response in the body: a tactic utilized by our immune systems to flush out infection and other foreign invasions. How might they be linked? How could depression or depressive symptoms have actually helped us to fight infection and survive?
First, take another look at the symptoms you experience when fighting a cold or other mild physical illness. There seems to be a large overlap with depressive symptoms: lack of energy, inability to find pleasure in activities you’ve previously enjoyed, irritability… These are not effects that the infection is having on you; these are the result of your body’s attempt to fight it. Furthermore, people suffering from depression have also been reported to have increased body temperature and reduced iron levels. These are actually steps the human body takes when you’re sick to eradicate a threatening foreign body. Even isolating yourself is a defence mechanism as it helps to prevent spreading your ailments to others in your social group, or even helps to avoid the stigma of being sick.
Depression in Relation to Inflammation
That being said, if the cause of depression were as simple as an untreated infection, we would have figured that out by now. However, the similarities between the inflammatory response, and the physiology of actively depressed people are far too many to disregard completely. So if not a response to an actual infection, is depression a reaction to a “false alarm”? If so, it seems that the most likely culprit that would fit the profile of this “false alarm” is chronic inflammation. Someone’s risk of depression increases as their biomarkers for inflammation increase.  Another demonstration of this link is the commonly understood association between obesity and depression. The higher your BMI (as flawed a metric as it is), the higher your risk of becoming depressed.  Interestingly, a correlation between BMI and inflammation has also been documented. 
So, here we are getting to the real heart of the issue. If unchecked inflammation can lead to depression, and kickstart the vicious cycle, how can we work to prevent it? First we need to look at what contributes to inflammation. Some of the most common causes of inflammation include, but are not limited to: smoking, sedentary lifestyle, psychosocial stress, lack of sleep, and a diet high in sugar. Fascinatingly, these are also risk factors for depression.  In combating chronic inflammation through diet and lifestyle changes, we are also working to reduce our chances of becoming depressed, or to attempt to treat active depression.
To us, this explanation finally answers how to believe having a healthy body actually leads to a healthy mind.
– Charlie & Cale
Coming Soon: How Getting Outdoors Can Prevent & Treat Inflammation
How Getting Outdoors Can Prevent and Treat Inflammation