Overwhelmed by stress, the brain can derail
Accelerated heart rate, shortness of breath, tense muscles … Stress ruins the life of more than one in two French people. saint elias cognitive Nicknamed the evil of the century, stress is essential to our survival. Thanks to the secretion of cortisol and adrenaline, it triggers the escape of prey from a predator or increases our vigilance against a danger. But when this state is prolonged, the body flanks. And first and foremost the brain, recalls the Federation for Research on the Brain (FRC) on the occasion of the national week dedicated to this essential organ (12 to 25 March).
“Stress is all situations that move us away from our point of balance. But when this imbalance becomes chronic and the person can no longer resist, harmful effects appear, “says Karim Benchenane of the Brain Plasticity Laboratory of the School of Physics and Industrial Chemistry (ESPCI) of Paris.
In rats, researchers have shown that long-term exposure to stress hormones (cortisol and adrenaline) causes dysfunction in the hippocampus, the seat of memory. Highly stressed laboratory guinea pigs have fewer neurons in this region than more relaxed animals.
A similar mechanism in humans, especially in patients with depression. Undergoing significant psychological stress, depressed people also exhibit atrophy of the hippocampus. “Depressives seem to have neuronal connections, also called synapses, disappearing into the hippocampus.” But memorization is done through the training and consolidation of these connections, “says Karim Benchenane who dedicates his research to memory.
Loss of connections and neurons
Some scientific work also suggests that depression affects the genesis of new neurons. A cellular loss that contributes to the appearance of cognitive, emotional and memory disorders. And the more resistant depression is, the more neurotoxic effects are observed. A French study by Professor Philip Gorwood has shown that the importance of cognitive disorders depends on the number of depressive episodes.
But good news this neurotoxicity is not definitive. Proper antidepressant treatment blocks the neurotoxic effects of stress. They also suggest that early management of depression would reduce these effects.
And why not act before the onset of depression? Tackle stress directly? “It is possible to prevent or compensate for the loss of synapses,” he says, “but it is often asked,” he said, “otherwise, it will be destroying those that are unused,” says Karim Benchenane.
On the subject, the scientific literature is unanimous: In addition, by stimulating the formation of new blood vessels in the brain, physical exercise promotes the birth of new neurons. Results: the volume of the hippocampus or gray matter increases. Memory disorders in depressives, and even Alzheimer’s patients, are diminishing. Benefits that also benefit the healthy.