Negative emotions and pathological aging

Negative emotions, anxiety and depression are thought to promote the onset of neurodegenerative diseases and dementia. But what is their impact on the brain and can their deleterious effects be limited? Neuroscientists at the University of Geneva (UNIGE) observed the activation of the brains of young and older adults when confronted with the psychological suffering of others. The neuronal connections of the older adults show significant emotional inertia: negative emotions modify them excessively and over a long period of time, particularly in the posterior cingulate cortex and the amygdala, two brain regions strongly involved in the management of emotions and autobiographical memory. These results, to be published in Nature Aging, indicate that a better management of these emotions—through meditation for example—could help limit neurodegeneration.

For the past 20 years, neuroscientists have been looking at how the brain reacts to emotions. “We are beginning to understand what happens at the moment of perception of an emotional stimulus,” explains Dr Olga Klimecki, a researcher at the UNIGE’s Swiss Centre for Affective Sciences and at the Deutsches Zentrum für Neurodegenerative Erkrankungen, who is last author of this study carried out as part of a European research project co-directed by the UNIGE. “However, what happens afterwards remains a mystery. How does the brain switch from one emotion to another? How does it return to its initial state? Does emotional variability change with age? What are the consequences for the brain of mismanagement of emotions?”

Previous studies in psychology have shown that an ability to change emotions quickly is beneficial for mental health. Conversely, people who are unable to regulate their emotions and remain in the same emotional state for a long time are at higher risks of depression. “Our aim was to determine what cerebral trace remains after the viewing of emotional scenes, in order to evaluate the brain’s reaction, and, above all, its recovery mechanisms. We focused on the older adults, in order to identify possible differences between normal and pathological ageing,” says Patrik Vuilleumier, professor in the Department of Basic Neurosciences at the Faculty of Medicine and at the Swiss Centre for Affective Sciences at the UNIGE, who co-directed this work.

The scientists showed volunteers short television clips showing people in a state of emotional suffering—during a natural disaster or distress situation for example—as well as videos with neutral emotional content, in order to observe their brain activity using functional MRI. First, the team compared a group of 27 people over 65 years of age with a group of 29 people aged around 25 years. The same experiment was then repeated with 127 older adults.

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