Image copyright eternalcreative via Getty Images

A Montreal researcher says he has found a way to take the emotional sting out a bad breakup by "editing" memories using therapy and a beta blocker.

Dr Alain Brunet has spent over 15 years studying post-traumatic stress disorder (PTSD), working with combat veterans, people who have experienced terror attacks and crime victims.

Much of his research has centred on the development of what he calls "reconsolidation therapy", an innovative approach that can help remove emotional pain from a traumatic memory.

At the heart of his work is a humble pharmaceutical - propranolol - a beta blocker long used to treat common physical ailments like hypertension and migraines, but which research now suggests has a wider application.

The reconsolidation method involves taking propranolol about an hour before a therapy session where the patient is asked to write a detailed account of their trauma and then read it aloud.

"Often when you recall memory, if there's something new to learn, this memory will unlock and you can update it, and it will be saved again," the Canadian clinical psychologist tells the BBC.

That process of reconsolidation creates a window of opportunity to target the highly emotional portion of that memory.

"We're using this enhanced understanding on how memories are formed and how they are unlocked and updated and saved again - we're essentially using this recent knowledge coming out of neuroscience to treat patients," says Dr Brunet.

His work has often been compared to the science fiction film Eternal Sunshine of a Spotless Mind, where an estranged couple have their memories of each other erased, though Dr Brunet notes memories aren't gone after reconsolidation therapy, they just stop hurting.

Image copyright Rex Features Image caption Kate Winslet and Jim Carrey play a couple who erased their memories of each other

Memories, their neutral, factual elements, are saved in the brain's hippocampus. But the emotional tone of the memory is saved in its amygdala.

"Imagine that you are shooting a movie in the old-fashioned way so you have the image and and the sound and they are on two separate channels," he says.

When a person relives their traumatic memory they experience both channels. Propranolol helps target one channel - the emotional aspect of memory - inhibiting its reconsolidation and suppressing its pain.

A memory recalled under the influence of the medication will then be "saved" by the brain in its new, less emotional version.

His research suggests about 70% of patients found relief within a few sessions of reconsolidation therapy.

Dr Brunet has collaborated with other PTSD researchers, including Harvard University's PTSD expert Dr Roger Pitman, in studying the method.

More recently, he launched a programme in France in the wake of deadly terror attacks in Paris and Nice, training some 200 doctors in the therapy to help treat victims, witnesses and first responders.

So far, over 400 people have undergone the therapy in that country as part of the programme.

Image copyright Getty Images Image caption Dr Alain Brunet's work with propranolol found the medication can affect memories

After showing success with post-traumatic stress, the doctor says he wanted to broaden the application for the treatment.

In 2015, along with one of his former graduate students, Michelle Lonergan, at McGill University in Montreal, he turned his attention to the broken hearted and their "romantic betrayals".

"If you look at Greek tragedies what are they of? Essentially betrayals," he says. "It's really at the heart of the human experience."

A bad breakup can also be tremendously painful, he notes, and people can feel emotional reactions similar to those seen in trauma survivors.

The patients they recruited for the study weren't suffering just a mild case of heartbreak. There were cases of infidelity. Some had been suddenly abandoned by someone they believed was a loving partner.

They were struggling to cope and were people who "cannot turn the page, they cannot get over it", says Dr Brunet.

"That's what people were constantly telling them, which is not helpful. But [their friends] are pinpointing the problem."

Image caption Dr Brunet hopes to treat phobias and addiction in a similar way

It was like the patients were "stuck in Groundhog Day" - the 1993 comedy where Bill Murray's character relives the same 2 February day over and over - but were instead stuck obsessively reliving their painful betrayals in their minds.

What he and Dr Lonergan found was that, like with PTSD, many of the heartbreak sufferers felt relief, some after a single reconsolidation therapy session.

After five sessions, when they read aloud the memory of their betrayal, they had the "impression that this could have been written by someone else - like reading a novel".

"This treatment approximates the normal working of memory, how we gradually forget and turn the page," he says.

His Montreal-based lab is currently recruiting about 60 people who have suffered infidelity or some other form of deception in a relationship for a new reconsolidation therapy study.

Dr Brunet is also hopeful the scope of reconsolidation therapy can be expanded further, used to treat phobias, addiction, complicated grief.

"Any type of distress which emanates from an emotional event," he says.