Genetic switch to turn off fear found

In a discovery that could spell the end for phobias, neuroscientists may have worked out how to silence the gene that feeds fear.
The breakthrough may help loosen the grip of fear-related memories, which are involved in phobias and conditions such as post-traumatic stress disorder, scientists say.
For many people, fear of flying or of spiders skittering across the lounge room floor is more than just a momentary increase in heart rate and a pair of sweaty palms.
It's a hard-core phobia that can lead to crippling anxiety.
Now an international team of researchers, including scientists from The University of Queensland's Queensland Brain Institute (QBI), may have found a way to silence the gene that feeds this fear.

The team has shed new light on the processes involved in loosening the grip of fear-related memories, particularly those implicated in conditions such as phobia and post-traumatic stress disorder, QBI senior research fellow Dr Timothy Bredy said.

Bredy said they discovered a novel mechanism of gene regulation associated with fear extinction, an inhibitory learning process thought to be critical for controlling fear when the response was no longer required.
"Rather than being static, the way genes function is incredibly dynamic and can be altered by our daily life experiences, with emotionally relevant events having a pronounced impact," Bredy said.
By understanding the fundamental relationship between the way in which DNA functions without a change in the underlying sequence, future targets for therapeutic intervention in fear-related anxiety disorders could be developed.

"This may be achieved through the selective enhancement of memory for fear extinction by targeting genes that are subject to this novel mode of epigenetic regulation," he said.
Xiang Li, the study's lead author, said fear extinction was a clear example of rapid behavioural adaptation, and that impairments in this process were critically involved in the development of fear-related anxiety disorders.
"What is most exciting is that we have revealed an epigenetic state that appears to be quite specific for fear extinction," Li said.
Bredy said this was the first comprehensive analysis of how fear extinction was influenced by modifying DNA.

"It highlights the adaptive significance of experience-dependent changes in the chromatin landscape in the adult brain," he said.
The study was published in the journal PNAS.