Fear is Part Normal Brain Function, New Study Suggests

Traumatic brain injuries may take up to years to heal and even after recovery, some patients are not the same.

For example, a psychological patient known only as SM is no different. SM suffers from a rare case of brain damage to her amygdala, an almond-region of the brain that according to a recent study published in December, makes her incapable of feeling fear.

For three months, scientists performed nearly everything they could imagine to scare SM. "We tried to use stimuli common in Western society," says Justin Feinstein, a graduate student and researcher from the University of Iowa who worked on the study. They walked with her through haunted houses, showed her horror films, and used other stimuli that would otherwise terrify the average person. They also asked her about fearful or scary moments in her past like when she was caught at knifepoint and gunpoint and nearly killed during a domestic dispute. Not once could they gather any evidence that she was scared, by her testimony or via theirs.

Researchers discovered that she wasn't afraid of anything, but rather, fascinated by scary situations in which other people may be afraid. Before her injury, she was horrified by snakes, but now, when the experimenters took her to a pet store, she was instantly attracted to the snakes and began to play with them. She even held up a snake and began playing with its tongue. She simply said that she was overwhelmed with curiosity when asked to explain her behavior.

The evidence suggests that our emotional reaction to danger is a mixture of both fear and fascination. When we find ourselves in potentially threatening situations, Feinstein says, "the amygdala helps us navigate the fine boundary between approach and avoidance." If the amygdala functions properly, these emotions, including fear, help in keeping us out of danger. However, when it is damaged, our response can jeopardize our survival, luring us to the things we should avoid. "The evolutionary value of fear is lost," deduced the researchers.

According to the Centers for Disease Control and Prevention (CDC), 1.7 million people sustain a brain injury each year. Of those, about 275,000 are hospitalized and 52,000 die. It is not clear how many people are being treated through other medical care or no care at all.

Other long-term consequences of brain injuries affect thinking, sensation, language and emotions according to the CDC website. Traumatic brain injuries may also cause epilepsy and increase the chances of getting Alzheimer's disease, Parkinson's disease and other brain diseases that become more prone due to age.

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