Summary: Increased sensitivity in the locus coeruleus-norepinephrine system in the brain drives the development of anxiety in depression. The findings shed new light on the neurobiological mechanisms behind stress resilience.
Source: University of Zurich
Researchers at the University of Zurich show that increased sensitivity in a specific region of the brain contributes to the development of anxiety and depression in response to real-life stress. Their study establishes an objective neurobiological measure for stress resilience in humans.
Some people don’t seem to be too bothered when it comes to handling stress. For others, however, prolonged 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 a group of medical students who are all about to face real-life stress for an extended period – during their six-month internship in the emergency room.
This is precisely the real-life situation on which a team of researchers involving Marcus Grueschow and Christian Ruff from the UZH Zurich Center for Neuroeconomics and Birgit Kleim from the Department of Psychology and the University Hospital of Psychiatry Zurich based their study.
Stress as a response to cognitive conflict and loss of control
Before starting their internship, the subjects were given a task that required them to process conflicting 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 of LC-NE activation – often referred to as the “firing rate” – varies from one person to the next.
Subjects 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 prolonged stress,” Marcus Grueschow summarizes their findings.
Objective measure predicting stress resilience
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,” Marcus Grueschow 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.
About this stress research news
Source: University of Zurich Contact: Marcus Grueschow – University of Zurich Image: The image is in the public domain
Real-world stress resilience is associated with the responsivity of the locus coeruleus
Individuals may show different responses to stressful events.
Here, we investigate the neurobiological basis of stress resilience, by showing that neural responsitivity of the noradrenergic locus coeruleus (LC-NE) and associated pupil responses are related to the subsequent change in measures of anxiety and depression in response to prolonged real-life stress.
We acquired fMRI and pupillometry data during an emotional-conflict task in medical residents before they underwent stressful emergency-room internships known to be a risk factor for anxiety and depression.
The LC-NE conflict response and its functional coupling with the amygdala was associated with stress-related symptom changes in response to the internship. A similar relationship was found for pupil-dilation, a potential marker of LC-NE firing.
Our results provide insights into the noradrenergic basis of conflict generation, adaptation and stress resilience.