Neuroscience of Anxiety: Simplified

What’s going on in the brain when one experiences anxiety?

Let’s explore the brain chemistry behind anxiety, related symptoms, and how anti-anxiety medications actually work. While anxiety is a complex condition that we still don’t know everything about, there are certain neuroscience concepts that I’ve summarized to help better explain what we do know about this mental illness.

What Is Anxiety?

Anxiety can take many forms, such as a general experience, in social contexts, related to separation, and more. It can be marked by feelings of tension, worry, restlessness, and somatic symptoms as well. Let’s explore the roots of this condition further.

Anxiety in the DSM-5

The Diagnostic and Statistical Manual of Mental Disorders (DSM-5) was created by hundreds of international experts on behavioral health with the purpose to improve diagnoses, treatment, and research. The manual is divided into different categories (e.g., bipolar and related disorders, depressive disorders, substance use disorders, etc.), and includes anxiety disorders:

  • generalized anxiety disorder
  • social anxiety disorder
  • panic disorder
  • post-traumatic stress disorder
  • separation anxiety disorder
  • substance/medication-induced anxiety disorder
  • specific phobia
  • agoraphobia
  • selective mutism
  • anxiety disorder due to another medical condition
  • other specified anxiety disorder
  • unspecified anxiety disorder

Anxiety: Built for Survival

A main theory on the function of emotions is that they evolved to efficiently organize cognitive functions. For example, if you come across an angry bear, you feel fearful. Fear quickens your thinking and activates your fight-or-flight response — and the same principle can be applied to anxiety, a form of fear. Anxiety may have began as an evolutionary advantage: worrying about danger leads to taking fewer risks, seeking safety, and acting with caution. While we may no longer routinely rely on anxiety for survival, it still functions for our safety.  Moderate anxiety is a normal human response that can serve to motivate and protect us. However, when unregulated, anxiety can create a heightened sense of fear and survival mode that can impair daily functioning.

Fear is anxiety that is attached to a specific thing or circumstance
(Horwitiz, 2013).

Generalized Anxiety Disorder (GAD)

When people speak about having “anxiety,” they’re most often referring to “generalized anxiety disorder,” or “GAD” for short. GAD involves excessive anxiety and worry, occurring for the majority of at least 6 months, about various events or activities (e.g., work or school performance). A notable feature about GAD is that the person has difficulty controlling their worry. Three or more symptoms must be present for the majority of 6 months:

  • restlessness or feeling “on edge”
  • irritability
  • difficulty concentrating or retrieving information
  • muscle tension
  • feeling easily fatigued
  • sleep problems (e.g., difficulty falling asleep, staying asleep, or restless sleep)

Additionally, the anxiety is not better explained by a medical condition, substance use, or other psychiatric condition.

How Common is GAD?

There are twice as many women diagnosed with GAD than men. While the onset of chronic anxiety is usually in childhood, most are diagnosed in their twenties. GAD tends to last life-long though it can be treated. However, only one in three people seek treatment. While GAD is a much more common occurrence in the population than people know, only in recent times has it been openly spoken about. The stigma surrounding anxiety, and mental illness at large, still hinders its discussion and treatment, though this is lessening over time.

Anxiety Regulation

The amygdala, found in the limbic system of the brain, plays a primary role in processing memory, emotional responses, and survival instincts. While the amygdala is responsible for emotional responses, including anxiety, it is modulated by the mPFC, or part of the brain that deals with executive function (e.g., impulse control, decision-making, planning, etc.).

Chronic Anxiety

When the amygdala is over-active it can lead to an exaggerated startle-response. It’s also been found that in people with chronic anxiety, the amygdala has increased dendritic branching while the medial prefrontal cortex (mPFC) has reduced dendritic branching.

The amygdala, roughly the size of an almond, is a mass of gray matter inside each cerebral hemisphere.

Neurotransmitters Involved

There are three neurotransmitters primarily involved in anxiety: GABA (Gamma-Aminobutyric acid), norepinephrine, and serotonin:

  • GABA: reduces the activity of neurons in the brain and central nervous system, resulting in increased relaxation, reduced stress, balanced mood, and pain alleviation
  • Norepinephrine: increases blood pressure, increases blood sugar
  • Serotonin: regulates mood, digestion, sexual function

Treatment Options

There are different methods to treat anxiety, such as with psychotherapy, medication, or a combination of both.


Mental health counseling can provide individuals with valuable insight and coping skills to better handle anxiety. Some effective therapies for anxiety are:

  • Cognitive-Behavioral Therapy (CBT)
  • Exposure therapies (especially with phobias & OCD)
  • Mindfulness- and relaxation-based therapies

Pharmacology Options

The first-line-of-defense medications for anxiety are SSRIs, or selective serotonin reuptake inhibitors. Following SSRIs are SNRIs (selective norepinephrine reuptake inhibitors, TCAs (tricyclic antidepressants), and MAOIs (monoamine oxidase inhibitors). For more information on these medications, visit my post on how the brain is affected by depression. If these medications aren’t effective in treating anxiety, buspirone (known as Buspar) may be used. Buspar is a “beta-blocker,” a medication that binds to epinephrine and norepinephrine in the body, reducing high blood pressure associated with anxiety. Additionally, the anxiolytic medication with the highest potential of abuse has become infamous in anxiety treatment — benzodiazepines.


Benzodiazepines (e.g., Klonopin, Xanax, Ativan, Valium) are often prescribed for anxiety as they have a rapid onset of action, muscle relaxant effects, and relieve anxiety well. However, they can be highly addictive. As they can also have potentially serious side effects and withdrawal, they are not recommended for long-term use. Benzodiazepines increase the affinity of the GABAA receptor for GABA, a neurotransmitter that increases relaxation, reduces stress, balances mood, and alleviates pain. They function similarly to alcohol and barbiturates (e.g., phenobarbital), which is why alcohol is often used to self-medicate anxiety calm one’s nerves.

Caution With Benzodiazepines

As benzodiazepines depress the central nervous system ( or “CNS,” comprised of the brain and spinal chord), they should not be taken with other CNS depressants like alcohol or opioids. Mixing them with other CNS depressants or overusing them can lead to overdose. It’s also critical that they not be suddenly discontinued as they can cause severe withdrawal symptoms such as seizures.

Ask questions about medications you’re prescribed so you can make informed decisions.

Your Relationship With Anxiety

As mentioned earlier, some level of anxiety is a normal human response that can serve to motivate and protect us. However, when unregulated, anxiety can create a heightened sense of fear and survival mode that can impair daily functioning. How do you experience anxiety? Where do you feel it in your body? Do you feel like it holds you back, is unregulated, or prevents you from feeling like yourself? If anxiety impairs your life, and you haven’t been able to control it, seeking treatment may be beneficial. As a therapist, a common rebuttal I hear to seeking mental health treatment is: “I don’t want to be put on medication.” This is a valid concern. Your treatment should be tailored for you, whether it involves psychotherapy and/or pharmacology. It’s important that you feel like your voice is heard in determining your treatment, and that you understand why your provider has made certain decisions.

Looking For A Therapist?

If you’re interesting in seeking help, you can begin by finding a therapist, psychologist, or psychiatrist near you. If you feel anxious about reaching out to providers, you’re not alone. Know that most are happy to have a brief phone consultation with you before you decide to meet them in person. This can provide you an opportunity to ask questions about their experience, share your reasons for seeking treatment, and see how you feel about your initial connection.

Mural in Downtown Boston : Summer 2018


  1. Horwitz, AV (2013). Anxiety: A Short History, Baltimore: Johns Hopkins University Press.

8 Comments Add yours

    1. Glad you enjoyed it, mom 🙂

      Liked by 1 person

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