A number of recent studies have found that it may be possible to selectively delete memories that trigger anxiety and post-traumatic stress (PTSD) without affecting other important .
After a traumatic event fear responses to dangerous situations are developed to benefit human survival. But what can be detrimental for humans is that sometime incidental information, known as non-associative memories, are retained and interrupt daily life through anxiety or manifestations of PTSD.
Scott Gardiner, an ex-soldier who served in Iraq, experienced heavy rocket attacks for up to 40 days during his tour of duty. Under heavy fire for long periods of time, soldiers were told to go about their daily routine.
“You could be eating your breakfast when a rocket attack comes in. So when you come back home, eating breakfast can be a big trigger,” Scott told Insight.
“Any little thing that you do in your everyday life becomes a trigger and that makes it very, very difficult to deal with.”
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When recording memories during traumatic events, the body experiences a fear reaction, better known as fight or flight. While normal memory recollection requires just the hippocampus, traumatic memories also engage with another part of the brain called the amygdala.
“The amygdala is very important in detecting threats and helping you remember those threats in the future,” Dr Elizabeth Phelps, a psychologist and neuroscientist at New York University told Insight.
“So it's actually interacting with the hippocampus that gives us those conscious memories of the episodes of our lives and it's helping you store those memories just a little bit stronger.”
Due to this stronger recollection of memory, when triggered, those suffering from PTSD often feel as though the event is happening now.
The problem with PTSD treatment now
Two forms of treatment are commonly used to overcome PTSD - exposure therapy and trauma-focussed cognitive behavioral therapy (CBT), a counselling approach.
During trauma-focussed CBT, a patient will confront memories and situations they have avoided since the event until they are no longer distressed by them.
“A hundred incidents could happen and you can't do exposure therapy on every single one of them."
Exposure therapy works similarly in a graded process designed to help patients physically confront objects, situations, memories or images that may evoke false danger.
Despite proven success, experts say it is not uncommon for both patients and professionals to struggle through the process of determining when to begin and if it is the best course for the patient.
Professor David Forbes, a clinical psychologist and the head of the Australian Centre for Posttraumatic Mental Health, believes professionals can’t rely on a textbook response each time.
“While we talk about exposure therapy being the best treatment we have for PTSD, it's always invariably got to be couched in establishing the relationship, getting trust, allowing the person to develop skills and strategies to manage anxiety, so that you together as a unit decide that we're ready to take the next step,” Dr Forbes told Insight.
Scott Gardiner, who has undergone some exposure therapy, says he has not yet regained control over his memories.
“A hundred incidents could happen and you can't do exposure therapy on every single one of them,” he said.
Scott Gardiner. Photo: Insight Source: Insight
Erasing memories
Brains create long-term memories by increasing the strength of connections between neurons (nerve cells) and maintaining those connections over time.
Previous research suggested that strengthening these connections for associative memories (important information about the event) and non-associative memories (information not directly related to the trauma) share common properties. New studies studies by Medical Centre and McGill University instead found the two types of memories are strengthened by different proteins.
By blocking the production of a specific protein, unwanted memories could be erased by weakening these connections.
A similar study by the University of California tested another method of weakening connections between nerves through optogenetics, a technique which uses light to modify cells such as neurons.
Mice trained to fear high-pitch sounds demonstrated that the technique could artificially weaken the connection associated with a memory, and hence, erase the fear itself.
