The anatomy of anxiety: How fear responses wire the nervous system for survival

Anxiety and trauma are more than a “mental health” matter

By Geraldine Naidoo

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Published: Tue 25 Jun 2024, 12:59 PM

In the shadowy corridors of the mind, something undistinguishable lingers. Fuzzy, inarticulate, and habitually indecipherable, it whispers harshly in the stillness of the night, and tightens its grip in the clamour of the day….

For millions, these whispers swell into the ruthlessness of full blown anxiety: a relentless concerto of uneasiness that will not loosen its vice-like grip.

But what is it that lies at the heart of this pervasive condition that we recognise as anxiety?

Leading trauma experts suggest that the answer lies deep within the brain's ancient wiring—an evolutionary legacy designed to ensure survival, but which often leaves us trapped in a loop of chronic stress and anxiety.

The Roots of Anxiety in Trauma

Dr. Bessel van der Kolk, a luminary in trauma research and author of the ground-breaking work The Body Keeps the Score, posits that anxiety is frequently a byproduct of unresolved trauma. Traumatic experiences, he explains, leave unforgettable marks on the brain, particularly in areas responsible for fear and stress responses. When a threat arises, the brain's alarm system—centred in the amygdala—springs into action, flooding the body with stress hormones to prepare for survival. Notably, he points out that the whole body has memory, and anxiety and trauma are more than a “mental health” matter, that is a full mind-body matter.

The Brain's Fear Machinery

The amygdala, often referred to as the “smoke detector” of the brain, is an almond-sized structure buried deep within the brain, and is central to processing emotions, especially fear. Dr. Joseph LeDoux, a neuroscientist renowned for his research on brain survival circuits, notes that the amygdala is pivotal in detecting threats and initiating fear responses. In individuals with chronic anxiety, this system becomes hypersensitive, triggering intense fear reactions, even to seemingly benign stimuli.

Complementing the amygdala's role is the hippocampus, responsible for contextualising and storing memories. Trauma can disrupt the hippocampus's functioning, blurring the lines between past and present dangers. The timekeeping part of the brain goes offline. This means that the person does not recognise that the trauma has actually passed, but lives as if they are currently under threat. This confusion often manifests as heightened anxiety, with the brain remaining on high alert, constantly scanning for threats that may actually no longer exist.

It is critical to note that the body has a superior intelligence, and the job of anxiety is to keep you safe. Too often, the reasons for these fears and lack of safety have been lost in time, as a lot of highly anxious people have suffered trauma during a preverbal stage of life, and no conscious memory exists of what the fear could actually be. Or it could be that the fear is so intense that it is safer for the person to not acknowledge its presence as that would be too overwhelming.

The Nervous System's Role in Anxiety

Dr. Stephen Porges, creator of the Polyvagal Theory, offers a comprehensive framework for understanding how the autonomic nervous system (ANS) contributes to anxiety. According to Porges, the ANS operates in three primary states:

1. Social Engagement System: Characterised by feelings of safety and calm, allowing for social interaction and relaxation.

2. Sympathetic Nervous System (Fight-or-Flight Response): Activated in response to perceived threats, preparing the body for immediate action.

3. Parasympathetic Nervous System (Freeze Response): Engaged in the face of overwhelming threat, leading to immobilisation and dissociation.

In individuals with chronic anxiety, the ANS frequently swings between the fight-or-flight and freeze responses, rarely settling into the social engagement state. This persistent state of hyper vigilance and fear conditions the nervous system to remain wired for anxiety.

The Role of the Physical Body’s Response in Anxiety

Trauma lands in the physical body, leaving layers of invisible bruises which keep you in a chronic state of collapse.

Dr David Berceli, renowned psychotherapist, explains that is a completely natural, genetic encoded reaction for the body to move towards a fetal position in relation to stress, anxiety and trauma. Over time, the resulting contraction of the deep postural muscles leads to a build-up of chronic muscular tension within the body, which leads to chronic pain/disease/pathology

Over time, this neurological separation can lead to continued "stuckness", as well as instinctual behaviours and emotions that include increased anxiety, impulsiveness and other stress-related conditions. The resulting limitation restricts not just physical movement, but also your movement into life itself, and can show up as lack of motivation, chronic procrastination

Research Insights

Numerous studies have illuminated the intricate relationship between trauma, fear responses, and anxiety. A pivotal study published in Nature Reviews Neuroscience revealed that childhood stress/trauma can induce lasting changes in the brain's fear circuitry. In other words, the brain becomes hard-wired for survival.

The researchers found that trauma can increase activity in the threat detection center, the amygdala, and decrease activity in the brains region responsible for executive functions and decision-making—leading to heightened fear responses and an inability to do anything” logical” about it.

Further, research published in Biological Psychiatry discovered that individuals with anxiety disorders often exhibit an overactive stress pathway, resulting in excessive stress hormone production which can intensify the physical manifestations of anxiety, such as rapid heartbeat, sweating, muscle tension, etc..

Pathways to Healing

Trauma experts agree that overcoming anxiety rooted in fear responses requires an integrative approach addressing both mind and body, because mind and body operate as one unit. Exploring a multi pronged approach is often necessary, as one modality may not provide the solutions you require.


Anxiety, deeply entrenched in fear responses, often becomes a chronic condition when, as a result of life experiences, the nervous system becomes primed for survival. Understanding the pivotal roles of the body’s survival mechanism offers crucial insights into the development and persistence of anxiety. By integrating body-based therapies and mindfulness practices, individuals can begin to heal from trauma and rewire their nervous systems for resilience and calm.

As research continues to evolve, the work of leading trauma experts remains indispensable in guiding effective interventions and offering hope to those ensnared by anxiety's grip.

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