Depression, Trauma + Inflammation : What's Their Relationship?

Introduction

Hi, Neil Shearing here from Epicentering with a video update for you. What I'd like to do in this video is continue to look at the causes of depression and specifically the relationship between stress, inflammation and trauma.

Now in a previous video, I was looking at the overlap between the symptoms of people who have viral illness and people who have depression. There are similarities between the two, and I thought maybe the common factor could be inflammation. Could it be that the distress that people encounter in their lives, which gives rise to inflammation and then depression could be similar to when people have a viral infection and have similar symptoms to those of depression?

Maybe the commonality was inflammation. So that's what the earlier video went into in detail. That video was called, "Is Depression a Mind Virus?" 

The Inflamed Mind

Now, a lot of the thinking that I've had around inflammation was triggered by this book, "The Inflamed Mind" by Professor Edward Bulmore. Very, very interesting book, highly recommend if you're into this specific subject.

There are several really interesting stories that he mentioned in the book. One of them was about a group of, I think it was 15,000 children in South West England, that they looked at at age nine. They were given a test for depression and they also looked at their circulating cytokine levels. So they looked at interleukin-6, which is a cytokine and a measure for their inflammation. And they found that those that had the highest levels of circulating interleukin-6 at age 9 went on to be the ones that were most likely to get depression at age 18.

Two Thirds Of Depressed People Are Not Inflamed?

There are lots of studies in the book, The Inflamed Mind, like that, that paint a picture of inflammation being critical to the story of how people develop depression. But one of the things that bothered me in the book was this paragraph where it says...

"To get a rough idea, let's start from the fact that about 350 million people, or 7% of the world's population, had an episode of MDD, Major Depressive Disorder, in 2012.

How many of these people would we expect to pass a blood test for inflammation? If we use CRP as the biomarker, [so in that study I was talking about they used interleukin 6, CRP, C -reactive protein, is another biomarker for inflammation.] and 3 mg per liter as the cut-off point for being inflamed, then we might expect about a third of the patients with MDD to be eligible for treatment with a new anti-inflammatory drug."

Now this kind of confused me because if inflammation is central to the story of how people end up with depression, how come only one third would actually pass this test for being inflamed? Now I don't know if 3 mg per liter is an appropriate cut-off point, I have to assume it is. But if you use that as a cut-off point, then this part of the book is saying that two-thirds of people with major depressive disorder wouldn't have CRP in the blood in excess of 3 mg per liter.

So two-thirds wouldn't pass this test. I thought that was really interesting and I was thinking why would that be? I've got here a model of depression, a simplistic model. You've got different types of stress, your psychological distress, emotional distress and physical distress.

Model Of Stress, Inflammation And Trauma In Depression

Psychological distress can be acute or chronic, so acute might be bereavement or a divorce, and chronic could be something like financial stresses or long-term being a carer for someone else. Physical stress would be something like an illness such as the viral illness and emotional stress is obviously the feelings that you have about any given situation in life and whether you can cope, so disappointments and powerlessness, worthlessness, feelings like that.

The stress that people are under comes in different formats and they obviously interrelate you know if you're having a strong viral illness then that's going to put emotional stress you're not going to feel good and psychological stress like bereavement causes feelings and emotions as well so they kind of interrelate which is why the arrows point between them.

But then the idea is they give rise to inflammation in the body, and inflammation in people who are susceptible causes depression, and depression can be self-reinforcing and get worse over time.

The question then is, why, if this model is correct, do only 33% of people with depression have that level of C-reactive protein if they were to test them?

Trauma As An Inflammation Sensitizer.

My idea is that maybe trauma acts as an inflammation sensitizer, so I'll explain that in a bit more detail.

Take this person for example. They have three units of inflammation, so just to make it simple, that would pass the test of three milligrams per liter of C-reactive protein in the blood. Say each of those blocks is one milligram per liter.

They have three milligrams per liter. They pass the test, CRP positive. They're depressed, and that story then would be that the inflammation is contributing to or causing the depression. But how about this person who only has one unit of the inflammation, so one milligram per liter in this simplified example?

They then would be depressed, but not have passed the test for the C-reactive protein. What if they had trauma that amplified the effect of the inflammation? So in this case, it tripled it, so there's one unit of inflammation, but three units of trauma.

So the trauma in this sensitive individual is amplifying the effect of inflammation in the body. Therefore, they're depressed, even though they didn't pass the test of three milligrams per liter of the C-reactive protein in the blood.

And then another example would be this person doubles the inflammation markers, so they've got two units of inflammation. Still not enough to pass the three migs per liter C-reactive protein test, but they're depressed.

Why are they depressed? Because the trauma, in this case, doubles their sensitivity to inflammation, and they effectively have four units of inflammation because the two of inflammation is doubled because of the trauma effect.

Conclusions

So this is how my thinking is evolving, that there's an interplay between the stress, the inflammation, and the trauma. And that could explain why only one third of people would actually pass this test of three mgs per liter of C-reactive protein in the blood.

And the two thirds that don't pass that test would have lower levels of circulating CRP, but then would be sensitive to it because of a past history of trauma. So this is, like I say, where my thinking's going.

Interestingly enough, in this book, The Inflamed Mind, as far as I can tell, it doesn't mention trauma.

So this trauma effect could be a missing piece of the jigsaw as to why two thirds of people with depression don't test positive or wouldn't test positive for inflammation, but are still depressed, despite inflammation obviously playing a really big role.

So maybe this trauma sensitizer effect is the missing part of this jigsaw. So I'd love to know what you think. Does this make sense to you? Do you think trauma plays a role in the development of depression and maybe acts as a sensitizer to inflammation going on within the body?

Let me know your thoughts.

Thanks for watching.

If you'd like to find out more about healing from depression, check out the free "introduction to epicentering: healing from depression course".