Phobias are a member of the family of anxiety disorders, and though the sufferer generally knows that his or her phobia is irrational, it can still be crippling. The fear of spiders, arachnophobia, may send people into a panic just from the sight of a spider in an enclosed terrarium, or even in a photo. But researchers have found that a two- to three-hour therapy session may be enough to treat arachnophobia and the effects could be long-lasting.

'[A]fter a two or three-hour treatment, they were able to walk right up and touch or hold a tarantula. And they could still touch it after six months. They were thrilled by what they accomplished.'

“Before treatment, some of these participants wouldn’t walk on grass for fear of spiders or would stay out of their home or dorm room for days if they thought a spider was present,” said study author Katherina Hauner in a news release. “But after a two or three-hour treatment, they were able to walk right up and touch or hold a tarantula. And they could still touch it after six months. They were thrilled by what they accomplished.”

Hauner and her team recruited 12 people with arachnophobia and first tested their fear response by having them look at pictures of spiders while their brains were being scanned. The parts of the brain involved in the fear response (the amygdala, insula, and cingulate cortex) were activated when the participants looked at the pictures. Then, the researchers had the brave participants attempt to get close to a tarantula in a terrarium: On average, they were not able to get within 10 feet of the terrarium before their fear stopped them.

Then participants each had therapy sessions, in which they learned about spiders and the typical behaviors of the creatures. The particpants learned that their fears were not based in reality, or on the actual behavior of spiders.

“They thought the tarantula might be capable of jumping out of the cage and on to them,” Hauner said. “Some thought the tarantula was capable of planning something evil to purposefully hurt them. I would teach them the tarantula is fragile and more interested in trying to hide herself.“

Over the course of their sessions, the participants were able to approach the terrarium, touch the tarantula with a paintbrush, and finally with their hands.

The effects of the therapy were seen in the brains of the participants: The fear centers mentioned earlier were much less activated when the participants looked at spider pictures after the therapy. The prefrontal cortex, which is responsible for higher-level processing and conscious thought, was also activated after therapy. Most of these effects lasted up to six months after the initial session, and may last longer.

Hauner says she was surprised to see the participants’ behavior after six months; “they walked right up to it and touched it,” she said. “It was amazing to see because I remembered how terrified they were initially and so much time had passed since the therapy.”  

Interestingly, the activity in the participants’ brains right after the therapy predicted how well the effects lasted over the six months. “This suggests that observations of brain activity immediately after therapy may be a useful future tool in predicting an individual's long-term outcome,” Hauner said. It will be interesting to see how the therapy fares over the very long-term, as studies looking further into the effects of concentrated therapy on phobias come out.

Hauner did the research while she was a graduate student at Northwestern University. The study was published in Proceedings of the National Academy of Sciences.