By Emma Young

That which doesn’t kill you makes you stronger… It’s an adage that’s backed up in part by studies of people who’ve been through a trauma, such as a car accident or a robbery. While it’s true that around 7-8 per cent of trauma survivors develop chronic PTSD and experience persistent intrusive, unwanted memories of the event, most people recover quickly, and some even report better mental health than they had before (generally when the trauma has been moderate, rather than severe). But what underpins so-called “post-traumatic growth?” A new paper in the Journal of Experimental Psychology: General, argues that it has to do with trauma triggering a form of mental training that increases some survivors’ control over their own minds.

“Our findings suggest that traumatic experiences – as horrible as they may be – might naturally contribute to the adaptation of cognitive control skills, thereby improving survivors’ later resilience, at least [for] those who experienced only moderate levels of trauma,” write Justin Hulbert at Bard College, US, and Michael Anderson at the University of Cambridge. If these researchers are right, there could be implications for the treatment of PTSD.

Two studies, each of 48 students, suggested that those who had experienced a relatively high number of traumas (including witnessing or experiencing accidents, violence, and the death of significant individuals) before the age of 18 showed a greater ability to inhibit, when instructed, their memories of a word pairing they had previously learned, compared with those who reported no or little trauma.

The participants initially viewed a set of 60 word pairs, which consisted of a neutral cue word (such as “violin”) and either a neutral or a negative response word (such as “street” or “corpse”). They were given up to three training cycles to correctly recall at least half of the response words. Next, they were given a series of “Think/No Think” trials. If a cue word was presented on the screen in green, they had to say the response word as quickly as possible. But if the cue word appeared in red, they were told to avoid both thinking about and saying the response word for the next four seconds. Then came some surprise recall tests. This time they were given either the original cue word, or a new semantic cue plus the initial letter of the response word – such as “anatomy c_____” for “corpse”.

Hulbert and Anderson found that while those in the high and low trauma groups were equally good at learning the initial word associations, those in the high trauma group showed superior performance on the subsequent “No Think” trials, indicating they had a “robust ability” to forget the specific response words when required to do so. This held for both neutral and negative words, “suggesting that this effect reflects a generalised skill at suppression, regardless of valence,” the researchers write.

The data is consistent with the idea that experiencing trauma – at least for this group of people who successfully made it to university – may encourage resilience by training the ability to inhibit unwanted memories, in particular, and perhaps even a general inhibitory control mechanism, which could extend to unwanted emotions and actions, Hulbert and Anderson propose.

If these new findings are reliable – and obviously the study requires that we trust the students’ self-reports of their history of trauma – then they could have implications for how to optimise CBT treatments for trauma. Standard cognitive-behavioural therapy for PTSD encourages patients to confront reminders of their experience and the memories that are triggered by them – the idea being that over time this exposure will lead the traumatic memories to become less distressing. However, Hulbert and Anderson believe their results suggest that while it is important not to avoid reminders of the trauma, it may actually be beneficial to practice suppressing the memories that are triggered by them (mirroring what seems to happen naturally for people who experience post-traumatic growth). “Training in retrieval suppression may augment the benefits of cognitive-behavioural therapy,” Hulbert and Anderson write, “by enabling patients to confront reminders and redirect to more benign thoughts.”

People who do not recover well from a trauma and who develop chronic PTSD may perhaps have general deficits in inhibitory control, or an impaired ability to adapt control mechanisms over time, perhaps in part because of a genetic variation in cortical plasticity, Hulbert and Anderson suggest. However, the new results suggest that “… for many victims living with trauma, efforts to achieve emotional balance by down-regulating intrusive thoughts may act as a natural form of cognitive training.”

—What doesn’t kill you makes you stronger: Psychological trauma and its relationship to enhanced memory control

Emma Young (@EmmaELYoung) is Staff Writer at BPS Research Digest