Some people don’t seem to be too bothered when it comes to handling stress. For others, however, exposure to stress can lead to symptoms of anxiety and depression. While stress resilience is a widely discussed concept, it is still very challenging to predict people’s individual response to increased levels of stress. Lab experiments can only go so far in replicating the chronic stress many people experience in their day-to-day lives, as stress simulated in the lab is always limited in exposure time and intensity.
It is possible, however, to observe groups of vulnerable individuals, such as medical students who are all about to face real-life stress for an extended period – during their six-month internship in the emergency room they face acute as well as chronic stress. This is precisely the real-life situation on which a team of researchers involving Marcus Grüschow, Christian Ruff and Birgit Kleim from the UZH Center for Neuroeconomics and Department of Psychology based their study.
“We are all equipped with the same basic stress response system, which has evolved over many years. The key question is whether and how some individuals use this system more effectively than others”, Marcus Grüschow comments. Before starting their internship participants were given a task that required them to process conflicting emotional information. This conflict task activates the locus coeruleus-norepinephrine (LC-NE) system, a region of the brain associated with regulating our response to stress and resolving conflict. However, the intensity – often referred to as the “firing rate” – of LC-NE activation varies from one person to the next.
Participants with a higher LC-NE responsivity showed more symptoms of anxiety and depression following their emergency room internships. “The more responsive the LC-NE system, the more likely a person will develop symptoms of anxiety and depression when they’re exposed to stress,” Marcus Grüschow summarizes their findings.
With their study, the scientists have identified an objective neurobiological measure that can predict a person’s stress response. This is the first demonstration that in humans, differences in LC-NE responsivity can be used as an indicator for stress resilience. “Having an objective measure of a person’s ability to cope with stress can be very helpful, for example when it comes to choosing a profession. Or it could be applied in stress resilience training with neuro-feedback,” Birgit Kleim explains.
This does not mean that aspiring doctors or future police officers will all have to have their brain scanned. “There might be an even more accessible indicator for stress resilience,” Christian Ruff says. Research with animals suggests that stimulation of the LC-NE system correlates with pupil dilation. “If we could establish the same causal link between pupil dilation and the LC-NE system in humans, it would open up another avenue,” he adds.
Marcus Grueschow et al. Predicting real-world stress resilience from the responsivity of the human locus coeruleus. Nature Communications. 15 April 2021. DOI: 10.1038/s41467-021-22509-1