Experiencing stress could be beneficial to people suffering from fear- and anxiety-related mental disorders. New research published in Psychoneuroendocrinology suggests that stress can disrupt fearful memories.
The study of 72 healthy men investigated how stress affects memory reconsolidation, a cognitive process where recalled memories are re-integrated into the brain. During this process, memories also become susceptible to revision and disruption.
The researchers expected that psychosocial stress would enhance the reconsolidation of reactivated fearful memories, making them stronger. Instead, they found that experiencing stress impaired the reconsolidation of fearful memories.
PsyPost interviewed the study’s authors, Shira Meir Drexler and Oliver T. Wolf of Ruhr-University Bochum. Read their explanation of the research below:
PsyPost: Why were you interested in this topic?
Drexler and Wolf: In our lab, we are interested in the ways by which stress and stress hormones affect various learning and memory processes. This field of study has relevance for the understanding and treatment of psychiatric disorders, such as anxiety disorders and post-traumatic stress disorder (PTSD). In the current study, we investigated the effects of stress on the reconsolidation of fear memories.
Reconsolidation is the post-retrieval process of re-stabilization of memories. Retrieved (often termed ‘reactivated’) memories are fragile to various manipulations until their reconsolidation process is complete. Thus, manipulations on reactivated memories are of potential benefit for treatment e.g. by impairing (or enhancing) unwanted (or wanted) memories.
We had previously investigated the effects of cortisol, which is the main stress hormone in humans, on the reconsolidation of fear memories. We found that cortisol administration leads to a specific enhancement of memories that were reactivated during the session. Other, related fear memories, which were not reactivated, were not affected. This is a possible mechanism for the persistence and strength of unwanted memories such as traumatic memories.
However, as opposed to a pharmacological intervention, an exposure to a stressor at the lab is more similar to real-life events as it leads to the complex stress response. Thus, in the current study we aimed to investigate the effects of mild stress on the reconsolidation of fear memories. Would the memory still be there after the manipulation? Would it be stronger or weaker?
What should the average person take away from your study?
Our results showed that stress disrupts the reconsolidation of fear memories. In the target group, which combined memory reactivation and stress, the fear memory was weakened and the fear response did not relapse. Importantly, this effect was general, also disrupting the fear memories that were not presented during the session. In the three control groups, in contrast, the fear memory was still present, as predicted.
The disruptive effect of a mild stressor on the reconsolidation of unwanted memories may have possible therapeutic implications for the treatment and relapse prevention of fear- and anxiety-related disorders. Currently, the rate of relapse is rather high even after successful treatment (e.g. exposure therapy). The generality of the disruptive effect found here is of particular importance. The ability to generalize safety from the stimuli presented during treatment to other stimuli is crucial for the prevention of relapse outside the clinic. For instance, in a treatment for spider-phobia, it is preferable that the fear reduction successfully achieved for one species of spider would generalize to other species of spiders as well.
Are there any major caveats? What questions still need to be addressed?
It is not clear why our current stress manipulation led to the opposite effects compared to our previous manipulation using cortisol. It is likely that the unique characteristics of the stress response and experience, compared to a pharmacological intervention, are the reason for these opposing findings. This has to be investigated in future studies.
Another important question here are the possible sex differences. In the current study we tested men only. However, women are at higher risk for anxiety-related disorders compared to men, and men and women might respond differently to a similar treatment. The findings of our study suggest a potential method for disrupting unwanted memories in therapy, yet we have to see whether similar effects can be seen in women.
Is there anything else you would like to add?
It is common to focus only on the detrimental effects of stress on our physical and psychological health. However, we have to remember that the stress response is usually adaptive, as it helps us to respond to life’s challenges and prepare us for future events.
Sometimes we find that stress and stress hormones might help us in unexpected ways. For example, new studies suggest that cortisol can improve the success of exposure therapy for anxiety patients, by making the safety memory (that is formed during treatment) stronger and more long-lasting. In addition, in our current study we demonstrated another way by which stress can be used to weaken unwanted memories and, possibly, improve our lives.
