Minus the fear: The new treatment could help treat disabling phobias as well as post-traumatic stress disorder, say researchers.
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SYDNEY: New research has found a drug-free way to conquer fear that may one day help treat sufferers of phobias and post-traumatic stress disorder.
The study, led by neuroscientist Marie Monfils of the University of Texas, in Austin, U.S., is the first to propose a treatment that permanently detaches fear from a memory, without the use of drugs.
Several drugs have been tested for their ability to 'cure' fear, but most are hard to administer to humans and can have harmful side effects.
Detaching fear from a memory
Many animals can learn to fear something, creating an association between a conditioned stimulus (CS), which in itself is harmless, and an unconditioned stimulus (US) such as something that causes pain. For example, people who survive car crashes are often scared thereafter of getting into a car, because of what the car reminds them of.
There are two methods that psychologists use for reducing fear associated with a memory: 'blockade of reconsolidation' and 'extinction.' The first is based on the memory's ability to change. After a memory is retrieved, there is a time-window during which drugs can erase it, permanently detaching the fear from the memory.
In the second, 'extinction', memory is recalled many times without the associated pain, gradually decreasing the expression of fear. But this method does not 'overwrite' the original memory; instead it produces a new memory that the stimulus can occur without the painful association (for example, 'sometimes car trips don't end in a crash').
This method is also not permanent, extinction studies in humans show that fear can re-emerge over time.
Mild electric shock
In the new study, published today in the U.S. journal Science, researchers combined aspects of both methods to treat rats that had learnt to associate a specific tone with a mild footshock.
First, Monfils and the team played the tone to the rats once (to "destabilise the memory"). One hour later, the researchers played the same tone repeatedly (as in the 'extinction' method).
Monfils believes the time delay between the first and second stimuli allows the 'reconsolidation' window to open up, allowing them to update the memory, like other studies using drugs have done. By the end of the treatment the rats were 'cured' – they no longer froze in fear on hearing the sound of the tone.
