There are thousands of known and studied phobias from aulophobia, a fear of flutes; to xanthophobia, a fear of the color yellow.
"We had somebody who was deathly afraid of people hiccupping," said Dr. David Barlow of the Center for Anxiety and Related Disorders at Boston University. "They would not put themselves in a situation where they might be around someone who would be likely to hiccup."
If a person knows what their fear is, they know how to avoid it. But for more than six million Americans with panic disorder, they can never be sure what will spark their fear or when it will come over them.
Lindsay Lanouette is the last person you'd think has any reason for fear or worry. The 16-year-old from Falmouth, Maine, is a great athlete, gets good grades and has many friends.
"Sometimes I have the fear of like -- that I'm gonna like die," she said. "I guess, like, cause, I won't be able to get help."
But her panic attacks can set in at any time. You can see it happening in English class when her legs begin to shake uncontrollably.
"I'm always, like, constantly moving my legs," Lindsay said. "I don't even know if it's like a nervous habit."
Her panic might arise during gym class, when her heart started beating faster.
"My heart kind of starts racing a little bit, I just get really nervous," she said.
Outside the familiar confines of school, her symptoms are even worse.
"When I go to the mall by myself, generally, it's like I get kind of dizzy," Lindsay said.
Lindsay's parents say she's been struggling with panic her entire life.
"Initially, it was just some separation problems with going to daycare or kindergarten," said Kathy Lanouette, Lindsay's mother.
"She'll say that her hands are tingly, her feet are tingly, she feels separated from her body," said Jason Lanouette, Lindsay's father.
Up until now, the family has tried to cope by keeping Lindsay out of places where she panics, like restaurants and movie theatres. But they can't protect her forever. She's almost old enough to go to college.
"I just worry about -- sometimes because I think sometimes she feels really bad that she has this and doesn't understand it," said Kathy Lanouette. "I just worry about some of the thoughts that she has said before -- you know, that she … doesn't want to live anymore."
Recently, the family received new hope. A friend told the Lanouettes about the Center for Anxiety and Related Disorders, located two hours away at Boston University. The center offers a five-day intensive treatment program for adolescents like Lindsay. Dr. Donna Pincus helped lead her through it.
"I'd like you to just almost be like a scientist with me," Pincus told Lindsay. "I want us to watch what happens and I want us to watch what happens right before you have a panic attack."
Doctors are still studying what causes panic disorder. One theory is that it has to do with the amygdala, the part of the brain that coordinates the body's automatic response to fear. Perhaps it activates too frequently in certain people.
"What we have to do together is teach that watchdog in your brain to not bark so much at times when there's not really any danger there," Pincus told Lindsay during one of their sessions.
Pincus and other doctors at the center placed Lindsay in the very situations that cause her the most panic.