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?
In a study from the University of Geneva and elsewhere, scientists found the activation of the brains of young and older adults when confronted with the psychological suffering of others.
The neuronal connections of older adults show strong emotional inertia: negative emotions modify them excessively and over a long period of time.
The effect was particularly strong in the posterior cingulate cortex and the amygdala, two brain regions strongly involved in the management of emotions and autobiographical memory.
These results showed that better management of these emotions—through meditation for example—could help limit neurodegeneration.
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 risk of depression.
In the study, the team 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.
The team found older people generally show a different pattern of brain activity and connectivity from younger people.
This is particularly noticeable in the level of activation of the default mode network, a brain network that is highly activated in a resting state.
Its activity is frequently disrupted by depression or anxiety, suggesting that it is involved in the regulation of emotions.
These connections are stronger in subjects with high anxiety scores, with rumination, or with negative thoughts.
However, older people tend to regulate their emotions better than younger people and focus more easily on positive details, even during a negative event.
But changes in connectivity between the posterior cingulate cortex and the amygdala could indicate a deviation from the normal aging phenomenon, accentuated in people who show more anxiety, rumination and negative emotions.
The posterior cingulate cortex is one of the regions most affected by dementia, suggesting that the presence of these symptoms could increase the risk of neurodegenerative disease.
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The study was conducted by Dr. Olga Klimecki et al and published in Nature Aging.
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