Fear And People Who Cannot Feel It

The People Who Cannot Feel Fear

Fear is a primal human instinct, an inheritance from our evolutionary past designed to ensure our safety. But what if this fundamental emotion was simply absent? For a tiny fraction of the population, an existence devoid of fear is their everyday reality. Their unusual conditions provide a unique window into the human brain, challenging our understanding of what it means to be afraid and forcing us to question the role of this powerful emotion in the modern world. Their stories illuminate the complex neuroscience behind one of our most basic feelings.

A Surgical Side-Effect

Consider leaping from an aircraft and experiencing no sensation. You would feel no surge of adrenaline, nor any acceleration of your heartbeat. This is the world of a man from Jarrow in South Tyneside, Jordy Cernik. He lost his sense of fear not through a genetic quirk, but as an unexpected consequence of medical treatment. Cernik was diagnosed with Cushing’s syndrome in 2005, an uncommon illness caused by dangerously high levels of the stress hormone cortisol. The illness caused rapid weight gain and constant sweating, among other debilitating symptoms. His arduous journey through treatment involved multiple brain operations and, crucially, a procedure to remove his adrenal glands.

The Fearless Father

The operations were successful in treating the Cushing's syndrome, but they came with a strange side-effect. In 2012, Cernik realised something was different. A trip to a theme park with his children felt strangely dull; the rollercoasters sparked no excitement. To test this new reality, he embarked on a series of daredevil acts. He skydived from 17,000 feet, used a zip-wire from Newcastle's Tyne Bridge, and rappelled from a 418ft tower in Northampton while connected to a heart monitor. The monitor flatlined, showing no response. The physical capacity for a fear response, driven by adrenaline from the glands he no longer possessed, was gone.

A Rare Genetic Blueprint

Jordy Cernik’s experience is exceptionally rare, but it echoes the lives of those with an even more unusual condition. The inherited genetic disorder is called Urbach-Wiethe disease, which is sometimes identified as lipoid proteinosis. Worldwide, medical records show documentation for only around 400 cases. A mutation in the Extracellular Matrix Protein 1 (ECM1) gene leads to the disease. This faulty gene causes the accumulation of a hyaline, or glassy, material in the skin, mucous membranes, and various internal organs, including the brain. The first sign is often a hoarse voice from birth due to deposits on the vocal cords.

Image Credits - by M Joko Apriyo Putro, CC BY-SA 4.0, via Wikimedia Commons

The Patient Identified as SM

The most famous person with this condition is a patient identified in research only by her initials, SM. The University of Iowa has been the site of intense study on her case since the 1980s, offering profound insights into the mechanics of fear. The gradual build-up of calcium deposits caused by her condition completely destroyed a specific part of her brain: the amygdala. This pair of small, almond-shaped structures, located deep within the brain’s temporal lobes, has long been identified as the epicentre of fear processing. SM’s unique case has allowed scientists a rare opportunity to study a human without a functioning amygdala.

Testing the Limits of Terror

A graduate student named Justin Feinstein joined the Iowa research team during the early part of the 2000s. He embarked on a mission to provoke fear in SM. Researchers showed her a battery of horror films, including The Silence of the Lambs and The Shining. They took her to a haunted house attraction and presented her with spiders and snakes. In every scenario, her reaction was not fear, but rather intense curiosity. Feinstein, who is currently a clinical neuropsychologist, observed her potent impulse to get closer and engage with the very creatures most people instinctively avoid, demonstrating a complete absence of apprehension.

The Brain’s Fear Centre

SM’s fearlessness stems directly from the destruction of her amygdala. A mutation in the gene known as ECM1 leads to a process of calcification that, in her case, targeted this brain region with remarkable precision. What fascinates researchers is the specificity of the damage. While SM cannot experience or recognise fear, her other emotions remain largely intact. She can feel happiness, sadness, and anger. This suggests the amygdala isn't the origin of all emotion, but rather a specialist, playing a crucial role in the brain's threat-detection system. Its destruction effectively silenced her internal alarm bell for external dangers.

An Inability to Learn Danger

The amygdala’s function appears more complex than initially thought. It is crucial for something scientists call fear conditioning—the process of learning to associate a neutral stimulus with a painful or frightening one. While SM has the intellectual knowledge that a heated pan causes burns, she is immune to conditioning that would create a physical fear response, like a racing heart, when faced with a trigger previously connected to pain. This deficit extends to social cues. SM is unable to recognise fearful expressions on other people’s faces, even though she can identify joy or sadness without difficulty.

The Social Perils of Fearlessness

This inability to read fear has profound social consequences. SM is described as extremely gregarious and sociable, yet she struggles to recognise and avoid dangerous people and situations. This has resulted in her being threatened with both knives and guns at different times. Her condition prevents her from sensing untrustworthiness in others. Researchers studying her sense of personal space found she was comfortable with a stranger standing just 0.34 metres away, almost half the distance preferred by healthy volunteers. This highlights how the amygdala functions within social interactions.

A Surprising Discovery

For decades, the research pointed to a simple conclusion: no amygdala meant no fear. An experiment led by Justin Feinstein, however, turned this idea on its head. Researchers asked SM to inhale a gas mixture with a high concentration of carbon dioxide. In healthy individuals, this can trigger a feeling of suffocation and panic. The team expected SM to remain calm. Instead, she had an episode of complete panic. She later described it as the most powerful fear from her entire adult life. Two other patients with the same condition had an identical reaction, proving the amygdala was not required for this type of fear.

Two Pathways to Panic

This startling result launched a decade-long quest for Feinstein to find answers. It revealed that the brain has two distinct fear pathways, which depend on the source of the threat. For external dangers—a snake, an intruder, a speeding car—the amygdala acts as the main conductor. It receives sensory information, detects a threat, and sends signals to the hypothalamus. This, in turn, engages the adrenal glands to release cortisol and adrenaline, triggering the classic "fight-or-flight" response. This is the pathway that is broken in patient SM.

The Body’s Primal Alarm

The brain handles internal dangers, like an increase of CO2 in the bloodstream, using a different method. High CO2 levels are perceived by the body as an indicator of imminent suffocation. Studies have demonstrated that the brainstem, not the amygdala, is responsible. This primitive region, which manages automatic functions like breathing, senses the internal crisis and initiates panic. Paradoxically, the amygdala appears to suppress this reaction. This is the reason individuals like SM, who do not have a functional amygdala, show a heightened and terrifying reaction to the CO2 challenge. The internal alarm sounds without a moderator to calm it down.

More Than a Single Story

Of course, conclusions drawn from a single individual require careful interpretation. Every brain injury is different, and the timing of the brain injury can affect the outcome. Another study involving identical twins who both have Urbach-Wiethe disease and similar amygdala damage found that one twin struggled to recognise fearful expressions, just like SM, while the other had no such difficulty. This shows the brain can adapt in varied ways. Nevertheless, SM’s case is extraordinary because the disease wiped out her amygdala so cleanly, leaving other brain regions largely untouched and providing a uniquely clear view of its function.

The Evolutionary Need for Fear

The remarkable stories of these individuals underscore the evolutionary purpose of fear. All vertebrates, from fish to mammals, possess an amygdala, demonstrating its deep evolutionary roots and its critical role in survival. It is an organism's primary defence mechanism against dangers from the outside environment. As Feinstein notes, an animal with a damaged amygdala returned to the wild usually perishes within a few days. Without the circuitry to navigate threats, animals place themselves in constant jeopardy. Fear, for all its unpleasantness, is a profoundly effective life-preserver.

A Modern Conundrum

Patient SM has survived for over five decades despite her condition. Her survival raises a provocative question: is our primal fear response still required for contemporary living? In societies where fundamental needs for survival are generally met and predators are no longer a daily threat, the fear circuit can seem overactive. Feinstein and other researchers suggest that this ancient system could now be more detrimental than beneficial, contributing to the soaring rates of conditions linked to stress and anxiety which plague the developed world. Our evolutionary shield may have become a psychological burden.

Image Credit - by Tatiana Sapateiro, CC BY 2.0, via Wikimedia Commons

New Hope for Anxiety Disorders

The insights gained from SM and others are shaping the future of mental healthcare. Understanding how the amygdala functions in anxiety is leading to innovative treatments. Therapies like cognitive behavioural therapy (CBT) and exposure therapy work by helping patients regulate their amygdala’s hyperactivity. More recently, technologies such as low-intensity focused ultrasound are being tested to directly and non-invasively dampen amygdala activity, showing promise for those with treatment-resistant depression and anxiety. This research offers hope for more targeted and effective interventions.

The Broader Picture of the Disease

While the absence of fear is the most striking neurological symptom of Urbach-Wiethe disease, it is not the only one. The condition affects the entire body. Patients typically present with a range of skin issues, including fragility, blistering, and scarring, particularly on the face and extremities. Small, bead-like bumps along the eyelids, known as moniliform blepharosis, are a pathognomonic sign. Dental problems, respiratory infections, and in some cases, epilepsy are also associated with the disease. There is currently no cure; treatment focuses on managing these diverse symptoms.

The Chemistry of Calm

Jordy Cernik’s story provides a different perspective on the biology of fear. His calmness comes not from a change in his brain’s threat-detection centre, but from a disruption to his body’s response system. Adrenaline is produced by the adrenal glands, and this hormone fuels the physical sensations of fear: the racing heart, the quickened breath. Without these glands, Cernik cannot generate this fight-or-flight chemistry. He reports that this affects more than just fear; he also experiences a lack of motivation and must work harder to generate an inner drive for daily tasks.

The Ethics of Fright

The study of fearlessness raises important ethical questions. The very nature of the research involves attempting to provoke terror in participants. With patient SM, scientists used stimuli they hoped would be frightening, from horror movies to live snakes. While SM herself was untroubled, the deliberate attempt to induce one of humanity’s most negative emotions in vulnerable individuals requires careful consideration. Researchers must balance the potential for profound scientific discovery with their duty of care to the unique individuals who make such work possible.

Redefining Human Courage

The existence of people who do not feel fear compels a re-examination of what we consider bravery. Courage is often defined as acting in spite of fear. If a person is biologically incapable of feeling fear, can their actions be considered courageous? Jordy Cernik’s daredevil stunts and SM’s resilience in the face of life-threatening events are remarkable. Yet their stories suggest that true courage may be less about fearlessness and more about the conscious decision to face a threat that one’s mind and body recognise as real and dangerous, a choice that is unavailable to them.

An Emotion for a Bygone Era?

The study of these rare cases provides an unparalleled glimpse into the machinery of emotion. It confirms that fear is not a single, monolithic feeling but a complex interplay between different brain regions and bodily systems. The research shows how an instinct forged over millennia for survival in a dangerous world continues to shape our modern lives. The remarkable lives of the fearless suggest that while our ancient alarm systems may not always be suited to contemporary society, they remain a fundamental part of what makes us human.