The sensation of fear is a common and essential aspect of human life, serving as a crucial mechanism for self-preservation and caution. However, some individuals experience a peculiar condition where fear is absent, a reality stemming from a rare medical condition.
Jordie Sarnik, a resident of the UK, was diagnosed with Cushing’s syndrome in 2005. This condition causes the body to produce excessive cortisol, a stress hormone. After undergoing a successful treatment involving the removal of his adrenal glands, Sarnik lost the ability to experience fear. This was evident when he rode roller coasters at Disneyland, skydived from airplanes, and rappelled from heights without showing any signs of fear – his heart rate remained normal, and he experienced no anxiety or distress.
Another case involves an American woman identified as S.M., who suffers from a rare genetic disorder called Urbach-Wiethe disease, also known as lipoid proteinosis. This disease leads to the destruction of the amygdala, the part of the brain responsible for processing fear. Scientists conducted various experiments on S.M., exposing her to frightening movies, haunted houses, snakes, and spiders. Despite the unsettling stimuli, she never displayed any fear, and in fact, showed a desire to get closer to the perceived threats.
S.M.’s behavior is notably distinct, often approaching people closely, regardless of their familiarity. In an experiment gauging personal space comfort levels, she indicated a distance of only 0.34 meters (approximately one foot), significantly less than the average individual. This illustrates that fear also plays a vital role in regulating social conduct.
In multiple instances, S.M. faced threats at knifepoint and gunpoint, but did not perceive the danger. This lack of fear led her into challenging situations.
Scientists suggest that fear operates through two primary mechanisms: one triggered by external threats (e.g., an animal attack) and another stemming from internal threats (e.g., suffocation or cessation of breathing). The amygdala is crucial for recognizing external dangers, while internal anxieties, like distress caused by increased carbon dioxide, are controlled by the brainstem.
In an experiment, when S.M. was exposed to carbon dioxide, she experienced intense panic and fear for the first time, demonstrating that fear is not solely dependent on the amygdala.
Scientist Feinstein postulates that an animal lacking an amygdala could perish quickly in the wild due to an inability to identify threats. However, S.M. has lived for over 50 years without an amygdala. These cases illuminate that fear safeguards us from harm while also influencing our social and emotional behaviors.
