Does Inflammation Cause Depression?

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Research is starting to show evidence that for some people with depression, one contributing biological cause may actually be inflammation. This new understanding can give you new tools to fight depression.

For decades we’ve been told in pharmaceutical commercials that depression is simply a chemical imbalance in the brain. And while that was perhaps an improvement on the previous idea that depression was a moral failing, it isn’t the full truth.

 Depression is an umbrella diagnosis; it’s a cluster of symptoms. When you get a depression diagnosis, your doctor or therapist has no way of telling you what is causing your depression. All they can tell you is that you currently have at least five out of nine symptoms. 

New research is demonstrating that depression, far from being one disorder, is most likely rooted in a variety of physical and psychological and social causes. And research is starting to show evidence that for some people with depression, one contributing biological cause may actually be inflammation. And this new understanding can give you a new tool to fight depression.

Inflammation may also play a big role in other mental health disorders like bipolar, anxiety, schizophrenia, OCD, autism, and PTSD. 

So let’s talk about what inflammation is, how it impacts mental health, and what we can do about it. 

How Is Inflammation Connected to Mood?

Have you ever caught a bad cold that made you extra sad or irritable or unmotivated? When you’re sick, your immune system creates an inflammatory response that makes you feel this way. 

But feeling down serves a function: to keep you in bed so that your body can devote its resources to fight off the virus and heal. And when the inflammation is gone, your mood bounces back and you get your energy back and you start feeling more cheery. 

It’s long been known that inflammation causes a depressed mood. People with high inflammation due to rheumatoid arthritis or cancer seemed to have good reasons to be depressed. 

Scientists assumed that it was a psychological response to the stress of being sick that was causing the depression. But as research has progressed, it seems that inflammation, stress, and mental health disorders all play into each other. 

Stress causes inflammation, being inflamed causes mood disturbances, and mood disturbances can lead to more stress, which creates a vicious cycle. 

So for example, when patients with rheumatoid arthritis, which is an inflammatory disease, began taking anti-inflammatory drugs, their mood lifted to the point of being euphoric. It was such a remarkable side effect that the nurses fought over who got to administer the medication. 

Now, depression and other mood disturbances aren’t just a psychological side effect of being sick; being sick and inflamed actually contribute physically to being depressed. 

What Is Inflammation?

So what is inflammation? It’s our immune system’s reaction to protect us from threats. 

When our immune system senses a threat, whether it’s a sprained ankle, a cut, or a virus, it sends inflammation to the area. Your immune system sends macrophages and lymphocytes to attack pathogens, and it makes the area heat up and swell. 

If the bacteria or other invader is spreading, the immune system communicates through the lymph nodes to heighten the inflammation response throughout the body. 

And this is one way that your body protects itself from threats and it heals and it stays safe. It’s a pretty incredible life-saving reaction. 

How Does Inflammation Affect the Body and Mind?

But when you’re chronically inflamed, your immune system remains in an activated state, and this can damage healthy tissues and interfere with healing. 

When inflammatory cytokines in the body reach a certain threshold, the vagus nerve sends a message to the brain to initiate its own inflammatory response, and this makes the macrophages get more angry and start to pump out cytokines. 

Now, these cytokines not only attack invaders like germs, but they can harm healthy tissues throughout the body and the brain. And this may be one explanation for the memory loss and cognitive impairment that come with chronic inflammation. 

Inflammation also lowers levels of serotonin, which can impact sleep and appetite and mood. 

But the awesome thing about the vagus nerve is that it sends information in both directions. It can send messages from the body to the brain to be inflamed, but it can also send messages from the brain to the body to lower inflammation. 

Numerous studies have linked depression and inflammation. One Danish study with over 70,000 participants showed that the higher the levels of CRP (an inflammation protein marker) in a person’s blood, the more likely they were to have self-critical and negative thoughts. 

Another study with over 15,000 children showed that kids with higher levels of inflammation were 50% more likely to be depressed by the time they turned 18. 

Another study showed that 45% of people with depression who did not respond to antidepressants had CRP levels higher than three milligrams per liter. 

What Causes Chronic Inflammation?

So what causes chronic inflammation? Infection, autoimmune disorders, diabetes, obesity, genes, and age are all things that can cause chronic inflammation, but stress is the biggest cause of inflammation. 

Your body interprets mental or emotional threats in the same way it does physical threats. 80% of depressive episodes are preceded by a stressful event like divorce or the death of a loved one. 

But it doesn’t have to be, like, this huge event to create an inflammatory response. Things like public speaking, peer rejection, or tight deadlines can all lead to a short-term elevated stress and inflammation response. 

Now again, stress and inflammation aren’t inherently bad. This reaction protected our ancestors from germs when they had no medicine, and our ancestors with the strongest inflammation response may have been more likely to survive injuries and illness, at least in the short term. 

And if someone felt sick and they felt down and discouraged and moody and they felt like withdrawing from the group, that may have protected others in their group from getting sick too. So inflammation and the depressive symptoms may have served a function. 

But in our modern day, the inflammatory response is very sensitive to things like public speaking, and that can lead to more suffering and depression and shorter life spans. 

Now, if you look at the list of things that cause inflammation, it seems especially relevant that things like abuse and trauma contribute to inflammation. 

How Does Understanding Inflammation Help Us Treat Depression?

So how does this help us treat depression? When it comes to depression, we need more treatment options that are more targeted and more effective than what we currently have. So that has led scientists to look at decreasing inflammation as one option. 

Now, right now treatment options are limited. Your doctor could test you for inflammation by checking CRP in a blood test, and if your levels are repeatedly over three milligrams per liter, it could be a sign of chronic inflammation. 

Findings suggest that people with a CRP greater than one, which is the cutoff for moderate inflammation, were less likely to benefit from SSRIs. And for these people, they may respond better to treatments that target inflammation rather than serotonin, or they may benefit from a tricyclic medication like nortriptyline. 

Now, some studies have shown that anti-inflammatory drugs used for rheumatoid arthritis, psoriasis, and asthma have mild antidepressant effects. Anti-inflammatory drugs are still not approved for depression treatment. 

Edward Bullmore, the author of The Inflamed Mind, where I learned much of this information, estimates that the first anti-inflammatory drugs for depression may come to market within the decade. 

Now, there are a lot of other things you can do to decrease inflammation. The first is, of course, managing your stress levels. Eating a healthy diet and exercising can also make a big impact. Omega-3 fatty acids can decrease the inflammation response for some people. 

And there’s also some evidence that vagus nerve stimulation using an implanted device that essentially calms the stress response, that that can help lower inflammation. But you can also train yourself to stimulate the vagus nerve with some activities that I teach in many of my videos, and that can also help in a big way with long-term stress.

Summary: Does Inflammation Cause Depression?

Long story short, inflammation may play a key role in mental health. The science behind it is just beginning to emerge. Getting your CRP levels tested may inform your treatment options, and learning to reduce stress and inflammation may be really helpful at treating depression and improving mental health in general. 

If you are looking for more resources to help with depression check out my course, Change your Brain, below.  I hope you found this helpful, and take care.

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