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Chronic inflammation is a sustained immune response in the absence of an acute cause. Anxiety is a sustained fear response in the absence of a tangible threat. Both are functions of the body’s own defenses going overboard and causing harm.

The link between inflammation and anxiety

Research shows that chronic inflammation and anxiety are tightly connected. The simplest indication of a link is that numerous studies have shown that patients suffering from a variety of anxiety disorders have high levels of inflammatory markers.

And a 2021 study of 144,890 patients from a British database called the UK Biobank found similar results, with interleukin-6 and C-reactive protein levels elevated in patients with depression and anxiety.

Does one cause the other?

Correlation between anxiety and elevated inflammatory markers establishes a connection between the two conditions that is too consistent to be coincidence, but it doesn’t say much about causality. Does anxiety cause inflammation? Or does inflammation cause anxiety? I doubt it will surprise you that our best evidence indicates that it’s a two-way street.

There is evidence that inflammation in the body can ignite anxiety in the brain. In animal studies, researchers have performed tests where they have introduced inflammatory cytokines into mice.

This influx of simulated inflammation causes the mice to display depressed and anxious behavior, which goes away when they are treated with anti-inflammatory cytokines.

Human studies have shown that inflammation related to sickness can drive shifts in mood, including depression and anxiety, among other negative consequences that researchers call “sickness behavior.”

On the other hand, chronic stress response is recognized as one of the primary causes of inflammation. Sure enough, chronic, persistent stress response has been identified as a cause of chronic inflammation. And as we know, while stress and anxiety aren’t identical, anxiety can worsen and prolong the bad effects of stressful periods.

Furthermore, negative emotions like anxiety have been shown to contribute to a slower wound-healing process, leading to a greater risk of prolonged inflammation. And mental health issues have also been associated with increased production of inflammatory cytokines in the absence of other sources of inflammation. In other words, an anxious brain can cause or worsen inflammation in the body.

Though there is clearly robust research confirming these relationships between inflammation and mental health, we’re still in the very early stages of fully understanding the exact pathways through which inflammation worsens anxiety (and vice versa).

Through imaging studies that monitor the way the brain reacts in the presence of inflammatory cytokines, researchers have found that inflammatory markers can lead to neurotransmitter imbalances, decreasing important chemicals like serotonin, dopamine, and GABA.

Furthermore, inflammation in the CNS can increase the responsiveness of the amygdala—which is a central nexus of anxiety—along with the responsiveness of other parts of the brain that play a role in mood and threat response.

The dangers of neuroinflammation

There is a specific type of inflammation that has special relevance to your brain: neuroinflammation. Just like it sounds, neuroinflammation is inflammation centered in your CNS, which consists of your brain and spinal cord.

Unlike your digestive tract, which is well equipped to deal with invading microbes that tag along in your food, your CNS is not designed to have contact with dangerous pathogens. That means that neuroinflammation is a very serious reaction, a last-ditch effort to protect your brain from harm.

Like inflammation elsewhere in your body, inflammation in the CNS starts out as a coordinated response to ward off harmful intruders.

The most important immune soldiers in your nervous system are oval-shaped cells called microglia, which perform several roles in neuroimmunity, including surveillance for threats, production of cytokines, and the macrophage-like work of gobbling up harmful pathogens and damaged cells. When they sense something is awry, microglia can marshal a powerful inflammatory response to help correct the problem.

Like inflammation in other parts of the body, this inflammatory response can be harmful as well as helpful, especially when it persists over long periods. Just as we saw with acute inflammation, in an ideal world, once the threat is neutralized, the inflammatory response is turned off, and the neurons of your CNS can go back to their everyday tasks of helping you think, feel, know, move, respond, and react.

If neuroinflammation grows unchecked because of chronic exposure to toxins or crossed wires in your immune system, serious problems can arise.

As we saw with peripheral inflammation, stress has been shown to be a major source of neuroinflammation, aggravating microglia in the amygdala, hippocampus, and other anxiety centers.

Again, this is a very new field of research, and I have a feeling we are only scratching the surface of understanding the full threat of neuroinflammation.

The takeaway

So, how can we use this information to make healthier choices? When it comes to the chronic inflammation that arises in your body, one of the best ways to reduce inflammation is to eat a healthy diet full of anti-inflammatory foods.

Thus, if eating poorly aggravates inflammation, and inflammation worsens anxiety, eating an anti-inflammatory diet will fight anxiety. And interestingly, recent research has shown that diet can also have a real impact on levels of neuroinflammation, potentially decreasing anxiety as well as the risk of other long-term neurological conditions.

Rather than focusing on the foods you eat, this research has focused on when you eat that food, studying the effects of dietary restriction through either reducing the amount of food you eat per day or limiting the time frames in which you eat.