What Causes Anxiety in the Brain?

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Anxiety is not fun. You probably already know that. If you experience anxiety, you are likely to find yourself wondering how to prevent any further instances of anxiety. You might ask yourself what caused your anxiety in the first place.

The answer is complicated. Genetics, trauma, and conditioning may all play a role in how we experience anxiety. What we do know is that there are ways to prevent anxiety and live a more productive life. Do you find yourself feeling anxious often? Learning the causes of anxiety is a great way to care for your mental health.

What Causes Anxiety in the Brain?

Triggers like a traumatic event or something we associate with trauma may set it off. The brain enters fight-or-flight mode and we experience anxiety. When this happens, we possibly set ourselves up to experience more anxiety in the future.

Fight-or-Flight and Anxiety

In the early days of humankind, we had a lot to be worried about. We were being hunted by carnivorous predators and warring tribes. Extreme weather threatened our lives. To protect us, our bodies developed the "fight or flight response."

The fight or flight response begins in the amygdala, part of the brain's limbic system. The limbic system is crucial for emotional processing.

When the brain senses danger, like a carnivorous predator, the amygdala prepares the body for fight or flight. Stress hormones like cortisol are released into the body. The pupils dilate. Heart rate and blood pressure soar. Pain receptors and certain bodily systems may shut off temporarily. All this is done to help the body fight or flee to safety.

You might have already noticed that these symptoms are very like the ones that we experience while anxious. Clammy hands, heightened senses, and twitchy muscles are also symptoms of anxiety. These symptoms directly harken back to what the body needed to do to run to safety in the face of danger.

These days, carnivorous predators are not a big part of our day-to-day lives, but anxiety is. So why do we continue feeling those symptoms of fight-or-flight? What causes us to get so stressed out?

External Events and Triggers

Before we go into what can cause anxiety over time, let's talk about "triggers" that may lead to anxiety. Some of these triggers are "stressful" events. Others simply affect the brain in ways that trick the amygdala into thinking that it's time to activate fight-or-flight mode.

We live in stressful times. The idea that we will default on a loan is stressful. Having a tough conversation with a loved one is stressful. Facing our fears is stressful. These events alone may be enough to trigger a fight-or-flight response and evoke feelings of anxiety.

The Amygdala Hijack

You might be thinking to yourself, "I know a pop quiz is not a carnivore. So why is my body reacting the same way?" Something in the brain may happen during fight-or-flight that explains our more "dramatic" responses.

Have you ever been in a truly terrifying situation, and your brain feels like it "shuts down?" You don't think, you just act. We've seen this happen to superheroes in movies over and over again. They make split-second decisions that feel automatic.

In truth, these decisions are automatic. The amygdala can "shut down" the cerebral cortex that handles reasoning and logic. This has been called "The Amygdala Hijack" by psychologists. Have you ever experienced anxiety and thought irrationally? No matter how hard you tried, you couldn't calm yourself down? That's because your cerebral cortex wasn't working in the way that it should.


Have you ever heard of the Little Albert experiment? In 1920, a behavioral psychologist named John B. Watson conducted the experiment. He struck a loud noise behind a child's head every time the child was exposed to a rat. The loud noise caused the child to feel anxiety.

Over time, the child was conditioned to feel anxiety every time that they saw a rat...or a bunny...or any fuzzy animal. We too may condition ourselves to feel anxiety when exposed to certain stimuli. Here's an example. If your body goes into fight-or-flight mode every time you talk to a professor, eventually the thought of them might trigger anxiety.

People rarely condition themselves to feel anxiety at the sight of anything or anyone. While unintentional, this type of conditioning can be powerful.


Do you or someone you know feel anxious after having caffeine? It's likely you do. Caffeine is a stimulant. When stimulants enter the body, they encourage the same type of bodily response as anxiety. A cup of coffee, for example, may increase your heart rate. Once this happens, the rest of the fight-or-flight responses may follow.

Other stimulants that may cause anxiety include Adderall, Ritalin, steroids, or even antihistamines. Yes, some of these medications may be helpful in treating other disorders or symptoms. No, not everyone will experience anxiety when taking them. But not all brains and bodies respond to different stimuli in the same way.

Hormones and Other Internal Factors

Fight or flight cannot be invoked without the help of hormones. Hormones are chemical messengers sent out from places like the amygdala. Estrogen and testosterone are hormones, but so are cortisol, GABA, and adrenaline. Our hormones play a huge role in our moods, growth, and physiological functioning.

Hormonal imbalances may be a direct cause of anxiety. On a good day, our hormones are balanced and there is no need for us to go into fight-or-flight mode. But hormones may fall out of balance because of stressful events or other factors. The menstrual cycle may lead to hormonal imbalances. Thyroid issues, chronic stress, or birth control may also lead to hormonal imbalances. With the "wrong" imbalance, you may experience anxiety or even a panic attack.

Hormones remain in balance when our bodies are healthy. Anything that threatens our health may actually be threatening hormone production and distribution. This is why keeping a healthy body and mind is so crucial to preventing anxiety!


Alcohol usage can cause anxiety by throwing our hormones out of balance. Abuse of alcohol over time can also harm the body's ability to distribute hormones. Have you ever heard of the term "hangxiety?" Experts believe that it is caused by hormones!

Here's how it happens. Alcohol consumption encourages the release of GABA. GABA is a hormone that inhibits nervous system activity. This can have varied effects. Slower activity causes you to react slower and lose your balance. But it can also keep the fight-or-flight response from making you feel anxious.

With so much GABA firing at the time of your alcohol consumption, your brain is drained by the time you wake up. Nothing is around to inhibit nervous system activity, so your brain is moving much faster than usual. Have you ever felt like your brain was moving a mile a minute, and all your worries and fears were coming to the surface at once? That's anxiety, and it may be the result of hormonal imbalance or alcohol withdrawal.

How to Prevent Anxiety

With all this in mind, let's wrap things up with some tips on how to prevent anxiety.

  • Continue to learn about anxiety. I bet you learned something new about how your brain contributes to those irrational feelings of anxiety. Keep learning! The more you understand anxiety, the sooner you can identify it.
  • Yoga, meditation, and breathing practices. The best way to return to "normal" after a fight-or-flight response is to convince your body and brain that you are safe. Take a deep breath. Take a slow, deep breath. You can't take a deep breath when you're being chased by predators! When the body and brain feel safe, they can go back to "rest and digest" mode.
  • Reach out to a professional. Medication can help to balance your hormones and keep your anxiety in check. To explore this option, reach out to a mental health professional.

Reference this article:

Practical Psychology. (2022, April). What Causes Anxiety in the Brain?. Retrieved from https://practicalpie.com/what-causes-anxiety-in-the-brain/.

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