My Stress Changes Your Brain

S u m m a r y :
Stress is not only contagious but it also changes the brain of the other person, says a new study published in the journal Nature Neuroscience.

My Stress, Your Brain

Stress is contagious. You would think this was bad enough, but no, there’s more bad news. Not only can stress ‘move’ from person to person, but it also changes the brain of the person to whom it is transmitted in the same way that it affects the one experiencing it. Or so says a new research conducted by investigators from the University of Calgary. It is to be noted that the experiments of the study are based on mice.

Females Are More Resilient…?

Oh, but yes, we do have a good news: the negative consequences of stress can be reversed through socialising; however, this was observed in female mice only, not in the males.

Stress Transmission in Mice Pairs

Stress-related brain modifications are known to be associated with mental illnesses like depression, anxiety disorders, and PTSD. This might be more complicated than previously thought, given that stress (together with emotions) may be contagious, explains study author Jaideep Bains. What remains to be investigated, though, is whether this comes with long-term effects or not.

Bains and his colleagues analysed the effects of stress in pairs or male and female mice: one mice from each pair was exposed to mild stress, and then returned to its counterpart. Thereafter, the responses of neurones controlling brain responses to stress (called CRH neurones) were examined in all mice. The results show that both the stressed mouse and its partner had modified brain networks; more interestingly, the alterations were the same.

“What was remarkable was that CRH neurons from the partners, who were not themselves exposed to an actual stress, showed changes that were identical to those we measured in the stressed mice,” says study lead author, Toni-Lee Sterley.

Turning Neurones Off: No Stress Transmission

As a further step, the scientists engineered the neurones to be able to switch them on and off with light. So, when the neurones were, thus, turned off during stress, the brain modifications that would otherwise occur in the aftermath of stress did not happen. Furthermore, when the neurones were silenced in the mouse-partner when it interacted with its stressed partner, the stress transfer did not occur either. On the other hand, when the neurones were activated with light in one mouse, regardless of the presence of stress, the brains of both mice were changed in the same manner as real stress would.

Upon further investigation, the team found that activated CRH neurones led to the release of a chemical called alarm pheromone which the mouse would use to alert its partner. When the latter would detect the signal, it would, in turn, notify other members of the group. According to the study authors, the stress signals propagating in such a way shows an underlying mechanism via which information is transferred, possibly with the aim of building social networks in many animal species.

Advantages of Socialisation

The formation of social links appears to have more than one benefit: it can also boost the ability of the animals to mitigate the unwanted effects of adverse events (here, stress). However, this stress buffering was selective, remarked Bains. It seemed to work only in females: the remaining effects of stress on the CRH neurones of females were reduced by around 50% after they spent time with unstressed partners, a process that did not reveal itself in males.

Stress and social interactions, thus, appear to be closely associated. The authors claim that the effects of such interactions might be long-lasting, maybe even affecting behaviour at a future time.

Does the Same Happen in Humans?

These findings are pertinent to humans; Bains suggests that similar effects may be affecting us as well.

“We readily communicate our stress to others, sometimes without even knowing it. There is even evidence that some symptoms of stress can persist in family and loved ones of individuals who suffer from PTSD. On the flip side, the ability to sense another’s emotional state is a key part of creating and building social bonds,” explains Bains.


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