A woman who literally leads a fearless life could provide insight to treating veterans and others with post-traumatic stress disorder.
University of Iowa researchers who have been studying the patient, identified only as S.M., have pinpointed the amygdala as the part of the brain that causes people to experience fear.
Studies have shown that the amygdala – an almond shaped brain region in humans – is responsible for generating fear reactions in animals, but human studies are rare, said Justin Feinstein, lead study author and a UI doctoral student in clinical neuropsychology.
The patient, a woman in her mid-40s, has Urbach-Wiethe disease, a rare condition that damaged her amygdala sometime in late childhood, probably after age 10.
Feinstein said only hundreds of people worldwide have the condition.
The patient was exposed to fear-provoking situations, including watching horror films and being taken through a haunted house.
At a pet store, although she professed to dislike spiders and snakes, she held one snake and moved to touch a tarantula, overcome with what she described as curiosity.
Her responses were akin to a child’s. The report noted the patient “displayed a compulsive desire to want to touch and poke the store’s larger and more dangerous snakes, even though the store employee repeatedly told her that these snakes were not safe and could bite. In total, SM asked 15
different times whether she could touch one of the larger snakes.”
She was stopped before she touched the spider.
Incidents in her past made Feinstein marvel that she is still alive; she lives independently, though he would not say where.
When she was 30, walking home alone at night, a man called her over to a park bench where he sat.
Most people would not have approached him, but she did. The man pulled out a knife that he held to her throat.
“S.M. claims that she remained calm, did not panic, and did not feel afraid,” the report noted. “In the distance she could hear (a) church
choir singing. She looked at the man and confidently replied, “If you’re going to kill me, you’re
gonna have to go through my God’s angels first.”
He let her go and she walked away.
One of her three adult children recalled his mother showing no fear as she picked up a “rather large snake” in the yard, but she did express other emotions, especially sadness and loneliness.
“One of the things I’ve been taken by is why is fear so important to people,” said Feinstein, who has been busy taking calls about the study, published Thursday, Dec. 16, in the journal Current Biology.
He speculated that had the study been about anger or other emotions, the interest level would not be as high.
Feinstein’s research dovetails with his current position, a one-year clinical internship in San Diego working with veterans who suffer from post-traumatic stress disorder, also known as PTSD.
Some of the patients cannot even leave their house because of the “ever-present feeling of danger,” he said. “You find the exact opposite (of S.M.) in PTSD.”
The disorder affects more than 7.7 million Americans, according to the National Institute of Mental Health, and a 2008 analysis predicted that 300,000 soldiers returning from combat in the Middle East would experience PTSD.
Feinstein said prolonged therapy exposure, in which patients are gradually reintroduced to situations, such as driving, holds promise for some PTSD sufferers.
Medications have also proven helpful, but can be addictive, he said.
“It would be great to find better treatments to help these people,” Feinstein said. “We should start tailoring our efforts toward treatments that target the amygdala.”
Those treatments would not go to the extreme of S.M., he said, but should be focused toward safely dampening amygdala activity.
Feinstein said studies are continuing with S.M. and researchers are trying to recruit other patients with similar conditions.
Skeptics who say the findings are diminished with just one patient need to understand the nature of brain research, Feinstein said.
“Case studies are the bedrock of understanding how the brain works,” he said, citing amnesia research in the case of a man who had part of his brain removed in the 1950s to relieve epilepsy symptoms. “You shouldn’t discount the revealing nature that a single patient can show the world.”The study was funded by the National Institutes of Health and a National Science Foundation Graduate Fellowship.