The thought of a lifeless rodent is enough to make Anna Dunn's skin crawl, but you won't see her jumping on a chair because it's her fear of heights she finds even harder to overcome.

And she far from alone: Twilight star Kristen Stewart is scared of horses; and Orlando Bloom is petrified of pigs. From Hollywood to households across the country, we're a nation that's afraid - very afraid.

Dunn, an avid dirt bike rider, says her fear is holding her back in life and on the track.

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"I quite often have a little teary meltdown, tantrums on the side of the track – my 'not coping mechanism', I don't cope at all," Dunn said.

But a new medical breakthrough could hold the answer to helping the one million Australians suffering from a phobia become fearless. The new therapy - known as fear extinction - is being developed by researchers at the Queensland Brain Institute.

According to Research Fellow Dr Tim Bredy "your experiences actually lay down a signature at the molecular level within the neurons of your brain. At the genomic level there's actually a trace of your life experience, and by understanding how that occurs we can target it preferentially and modulate memory."

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This means Dunn's fear of heights in the future could be re-written by targeting a specific area of her brain.

Dr Bredy hopes negative associations can be targeted with a new drug.

"Ideally during the course of an exposure therapy session you would be able to give a person this drug, which targets this neural process specifically, and you would be able to enhance their memory for that experience during exposure therapy," he said.

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Still in the experimental stages, a phobia pill is still at least five years off. Until it's perfected Dunn will have to continue to overcome her fears on her own.

"I think it will expedite treatment for sure, it'll make it faster, so you will require less visits to the doctor's office. But you will also benefit from stronger control or regulation over the fear related memories," Dr Bredy explained.

More stories from reporter Damien Hansen

This reporter is on Twitter at @DamienHansen7