Study finds trauma of 2015 Paris terror attacks altered survivors' brains

Scientists looked at how post-traumatic stress disorder affected those who witnessed ISIS massacre

The ISIS attacks in Paris in November 2015 killed more than 130 people. Reuters

Many survivors of the 2015 Paris terror attacks were left with “compromised” brain functions due to post-traumatic stress disorder, a study has found.

Scientists who measured the brain activity of more than 100 survivors of the November 2015 massacre said many could no longer suppress traumatic memories as well as before. Some people's PTSD improved within three years of the attacks, while others continued to suffer from chronic stress.

MRI scans revealed changes in the brain's memory control circuits. Some survivors of the ISIS attack, in which 130 people were killed, experienced “intrusive memories” during a task in which they were supposed to block images out of their minds.

Those memories typically involve “intense and uncontrollable negative emotions, such as fear and sadness, profound distress, and the sensation that the traumatic event is happening again”, according to the study published on Wednesday by scientists in France and Switzerland.

Parisians witnessed violence spread across the French capital on the night of November 13, 2015, as gunmen opened fire at the Bataclan concert hall and in bars and restaurants. A bomb was also detonated at the Stade de France during Europe's worst terrorist attack in more than a decade.

Salah Abdeslam, the only known surviving gunman, described himself in court as an “ISIS soldier” during a trial which ended in a life sentence on murder and terrorism charges. Nineteen other people were found guilty over preparations for the attack.

Survivors who testified in court gave harrowing accounts of how they “played dead” for hours to avoid being shot by the terrorists. One who suffered permanent injuries told of his struggle with “survivor's guilt” and with images that continued to haunt him from the attack.

A total of 114 survivors took part in the brain study, about half of whom were diagnosed with PTSD and the rest classed as “resilient”. A year after the attacks, members of the first group “exhibited compromised brain dynamics, failing to distinguish between intrusive and non-intrusive conditions”.

Survivors were tested again two years later, by which point about 20 people's post-traumatic stress had gone into remission but more than 30 others were still suffering from chronic PTSD. “Notably, participants with PTSD in remission had a rebalancing of their memory control mechanisms within two years”, scientists said.

All those taking part in the study were French, aged between 18 and 60 and had no history of psychiatric or memory problems. Compared to a control group of people not exposed to the Paris violence they showed an “imbalance” in their ability to control intrusive memories.

The results demonstrate “the major role of the memory control mechanisms to the persistence of traumatic memory in PTSD”, the authors believe. They said their study could pave the way for new treatments to make survivors of traumatic events more resilient.

France separately marked 10 years on Tuesday since the shooting at the offices of satirical magazine Charlie Hebdo. The gunmen, who claimed to represent Al Qaeda in the Arabian Peninsula, said they were taking revenge for cartoons depicting the Prophet Mohammed.

The study, Plasticity of human resilience mechanisms by Giovanne Leone et al, is published in the journal Science Advances on Wednesday.