It turns out facing your fears really does work—researchers at Northwestern University have found that just one positive exposure to spiders had lasting effects in people with arachnophobia six months later.

The parts of the brain responsible for producing fear remained relatively inactive six months after patients underwent a single two-hour "exposure therapy" session in which they were able to touch a live tarantula. The brain changes were seen immediately after therapy and remained essentially the same six months later, according to Katherina Hauner, lead author and therapist of the study, which appears in Monday's Proceedings of the National Academy of Sciences.

"These people had been clinically afraid of spiders since childhood … they'd have to leave the house if they thought there was a spider inside," she says. According to the NIH, about 8 percent of people have a "specific phobia," considered to be a "marked and persistent fear and avoidance of a specific object or situation."

Over the course of two hours, participants touched a live tarantula with a paintbrush, a gloved hand, and eventually their bare hand. "It's this idea that you slowly approach the thing you're afraid of. They learned that the spider was predictable and controllable, and by that time, they feel like it's not a spider anymore."

The study sheds light on the brain responses to fear and the changes that happen when a fear is overcome. Immediately after therapy, activity in the participants' amygdalas, the part of the brain believed to be responsible for fear responses, remained relatively dormant and stayed that way six months later when participants were exposed to spiders.

Hauner says the study proves that exposure therapy works and can potentially be used to develop new treatment methods for people with extreme phobias. She says a similar method can be used on people with fears of confined spaces, heights, flying, blood, and more.

"It has to be an innocuous object or situation—it's not a phobia if you're scared of sharks and don't want to go in shark-infested water," she says. "That's called being safe."

In the near future, therapists might be able to inhibit the part of the brain responsible for fear or stimulate the region of the brain responsible for blocking fear in order to begin new therapies.

"There's already techniques we use to stimulate regions of the brain to treat depression and [obsessive-compulsive disorder]," she says. "It's not too far off in the future that we can use these techniques to treat other types of disorders."