Paris attacks: The anxiety of 'bearing witness'

The Paris attacks, carried out by gunmen and suicide bombers, left 129 people dead and hundreds injured.

Reports from the scene show people traumatised by what they witnessed.

Rolling news and social media posts means millions of people around the world have spent days deeply involved in the events in France.

For those people, unable to help on the ground and fearful of the future, there is a sense of powerlessness.

Keeping up to date with the latest news and finding out about the victims can give people a sense of "bearing witness" says psychologist Dr Pam Ramsden from the University of Bradford.

For a small number of these people, seeing the death and destruction online and on television can be harmful.

"Because we're watching it and seeing people who are directly affected, what we have a tendency to do is place ourselves in those positions and that's where the PTSD comes from," she says.

PTSD, or post-traumatic stress disorder, is an anxiety disorder caused by distressing, stressful or scary situations.

Violent assaults, sexual abuse, military combat and natural disasters are some of the things that can cause people PTSD. There are many symptoms, including insomnia, flashbacks and changes in mood.

According to Dr Ramsden, approximately one in 10 people who sees distressing images, like some of the ones that emerged from the Paris attacks, can show symptoms of PTSD after being exposed.

"What people have a tendency to do is start thinking about changing what they do, not gathering in crowds, where a terrorist could strike," says Dr Ramsden.

This behaviour isn't necessarily confined to people who have been directly affected by the attacks.

She says a proportion of people in the UK could start making different decisions, based on their fears.

The vast majority of social media users however, will be able to "take back" control and go on with their normal lives after seeing this kind of footage. Some even become defiant.

"There's a bunch of different reactions but there's going to be a group of people who are profoundly affected and that's exactly what I found in my study," she says.

She surveyed 189 people about their reactions to a range of events. When her study was published earlier this year, some people found the idea that PTSD could be triggered by social media.

At the time, Walter Busuttil of veterans' mental health charity Combat Stress told BBC Trending vicarious PTSD is a well established phenomenon. Vicarious PTSD is where you may not directly experience what has happened but through looking and hearing the experiences of others, it is as if you were there.

"There is a level of resilience that may be very high in some people and very low in others, and social media may actually affect particularly vulnerable people," he said.

That's an idea Dr Ramsden agrees with.

"The human brain is developed and designed for visual images. We process visual images the best of all of our senses," she explains.

The BBC offers support to employees who have to view distressing images as part of their role.

If, a couple of weeks after witnessing distressing images and video, you are still affected by feelings of anxiety, Dr Ramsden says you should "seek someone to talk to".

She adds: "If we know that our journalists are affected in this way, why wouldn't the general population be? They get zero support."

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