Scared of spiders? You can escape that web

People undone by arachnophobia holding a huge, hairy tarantula in their bare hand? No worries, not after a single brief therapy session changed the brain's fear response in adults with the lifelong, debilitating phobia of spiders.

The "exposure therapy" was small, done on 12 adults, but all of them held or petted the spider afterward, the study from the Northwestern University Feinberg School of Medicine reported Monday. One participant celebrated by getting a spider tattoo after having been unable to even look at photos of spiders.

"A lot of people are afraid of spiders, but in order to meet the criteria (for a phobia), it has to be a clinical diagnosis and interfere with your life," says author Katherina Hauner, a postdoctoral fellow in neurology. "One participant would avoid walking in grass. Another, if he thought the spider was in the room or house, would have to leave the house for days."

Fear of spiders is a subtype of an anxiety disorder called specific phobia, one of the most common anxiety disorders, which afflicts about 7% of the population, the study says. Common specific phobias also include fear of blood, needles, snakes, flying and enclosed spaces.

Tarantulas are "docile," Hauner says, and would rather get away from a human than hunt one.

This is the first study to document the immediate and long-term brain changes after treatment and to illustrate how the brain reorganizes long-term to reduce fear as a result of the therapy, the study says. The findings show the lasting effectiveness of "short exposure therapy" for a phobia and offer new directions for treating other phobias and anxiety disorders.

"Everyone would come in thinking: 'I'm going to be the one who can't do this. There is no way," Hauner says. "They were impressed by the end."

In therapy lasting two to three hours, which is different for each person, the participants were taught that troublesome thoughts about tarantulas were untrue. "They thought the tarantula might be capable of jumping out of the cage and on to them," Hauner said.

Exposure therapy gets its name from exposing a patient to what he fears, says Todd Farchione, research assistant professor at the Boston University Center for Anxiety and Related Disorders. "A lot of it is about dispelling people's beliefs. You can get significant changes in a short period of time."

They learned to approach the tarantula until they could touch the outside of the terrarium. Then they touched the tarantula with a paintbrush, a glove and eventually pet it with their bare hands or held it.

Immediately after, an MRI scan showed the brain regions associated with fear decreased in activity when people encountered spider photos.

When the same people were asked to touch the tarantula six months later, "they freaked out in a good way," Hauner says. "They said they couldn't believe they were doing this."