Dementia and neurodegenerative diseases are thought to be accelerated by negative emotions, such as anxiety and depression. But how do they affect the brain? Could be it possible to limit their negative effects?
Neuroscientists at the University of Geneva (UNIGE) observed the activation of the brains of young and old adults when confronted with the psychological suffering of others. The results suggest that better managing these emotions, such as through meditation, could help limit neurodegeneration.
The neuronal connections of older adults exhibit significant emotional inertia. Negative emotions modify them excessively over time, particularly in the posterior cingulate cortex and the amygdala, two brain regions heavily involved in emotion management and autobiographical memory.
Emotional Stimulus Brain Response
Neuroscientists have been studying how the brain reacts to emotions for the past 20 years.
“We are beginning to understand what happens at the moment of perception of an emotional stimulus. 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,”
said 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.
Previous psychological research has shown that the ability to change emotions quickly is beneficial to mental health. People who are unable to regulate their emotions and who remain in the same emotional state for an extended period of time are at a higher risk 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 aging,”
Patrik Vuilleumier said. Vuilleumier. is a professor at the Faculty of Medicine’s Department of Basic Neurosciences and the UNIGE’s Swiss Centre for Affective Sciences, and he co-directed this study.
Brain Network Patterns
The scientists showed volunteers short television clips depicting people in emotional suffering, such as during a natural disaster or distress situation, as well as videos with neutral emotional content, in order to observe their brain activity using functional MRI.
First, the researchers compared a group of 27 people over the age of 65 to a group of 29 people around the age of 25. The experiment was then repeated with 127 elderly people.
“Older people generally show a different pattern of brain activity and connectivity from younger people,”
said first author Sebastian Baez Lugo, a researcher in Patrik Vuilleumier’s lab.
This pattern was most noticeable in the level of activation of the default mode network, a brain network that is highly activated during rest. Its activity is frequently disrupted by depression or anxiety, implying that it is involved in emotional regulation.
“In the older adults, part of this network, the posterior cingulate cortex, which processes autobiographical memory, shows an increase in its connections with the amygdala, which processes important emotional stimuli. These connections are stronger in subjects with high anxiety scores, with rumination, or with negative thoughts,”
Posterior Cingulate Cortex
However, older people typically have better emotional regulation than younger people and can focus on positive details even during a negative event.
Changes in the connections between the posterior cingulate cortex and the amygdala, on the other hand, may indicate a deviation from the normal aging process, which is made worse in people with more anxiety, ruminating, and negative emotions.
Given that the posterior cingulate cortex is one of the regions most affected by dementia, the presence of these symptoms may increase the risk of neurodegenerative disease.
“Is it poor emotional regulation and anxiety that increases the risk of dementia or the other way around? We still don’t know. Our hypothesis is that more anxious people would have no or less capacity for emotional distancing. The mechanism of emotional inertia in the context of aging would then be explained by the fact that the brain of these people remains ‘frozen’ in a negative state by relating the suffering of others to their own emotional memories,”
said Sebastian Baez Lugo.
Targeting Emotional Inertia
Could dementia be prevented by targeting the mechanism of emotional inertia? The research team is currently conducting an 18-month interventional study to evaluate the effects of both learning a foreign language and practicing meditation.
“In order to further refine our results, we will also compare the effects of two types of meditation: mindfulness, which consists of anchoring oneself in the present in order to concentrate on one’s own feelings, and what is known as ‘compassionate’ meditation, which aims to actively increase positive emotions towards others,”
the authors write.
This study is part of a large European study, MEDIT-AGING, which aims to assess the effectiveness of non-pharmaceutical interventions for healthier aging.
- Baez-Lugo, S., Deza-Araujo, Y.I., Maradan, C. et al. Exposure to negative socio-emotional events induces sustained alteration of resting-state brain networks in older adults. Nat Aging (2023).