Stress, reduced to its simplest form, is the fact of being in an environment that does not suit us, confrontation with events as unpleasant as sugar in his coffee if you are a PhD student, or a sudden change of temperature below 0 ° C if you are a tropical species. The appearance of a stress in the life of an organism (population) will have different possible consequences, it is important to consider with the eye of an evolutionist. The duration of the stress will determine many things, including the response that is mobilized, and therefore the effects on the population. Besides, as stress is biotic (predators or pathogens) or not, the situation is quite different.
We can distinguish, with a spoon, two situations. In the first, we manage stress, and a simple adjustment of physiology enough to get by. If the temperature increases, we can always respond by producing halos (say, under the arms) as unsightly as they are physiologically justified. Even if the answer is not, a priori, selective, we do have a price in terms of fitness, the fitness that determines whether or not we pass our genes (try to land someone preceded by a good old smell of perspiration if you doubt the previous point). The second situation is more difficult: no one is doing more by responding with a slight adjustment of its physiology, it must now be genetically adapted to the new situation in order to survive: stress will become a selection factor, which will lead to the elimination of susceptible individuals in the population.
If the intensity of stress is a factor that determines whether action selection, the exposure rate is also crucial: even if a stress is very important, if not longer applied, or not often, the effect of selection may be minimal. And if the alternating stress (that is, if we oscillate around the optimum), it may take something quite interesting: the selection of different strategies. We saw the two main types of strategies that could be met: either we face stress (resistance), or you live with the consequences (tolerance).
One issue that arises when one is an organization that wants to survive stress and is of course "how we get out? ". By what devious trick we going to get out of this predicament? The answer is pretty obvious. If we want to resist stress, it is a busted adaptive mutation, and the best way to do this is to go as soon as possible to accumulate mutations. Particularly in bacteria, increasing the mutation rate has an important adaptive value in the context of stress (1). An interesting way to quickly acquire mutations is to divide more quickly, ie to increase its growth rate. We have the assurance of having left descendants, and the more you increase the chances of hitting a beneficial mutation.
You see that we must listen to those who tell you that there is no better anti-stress than sex!
Except that, as always, there are parasites. By definition, the parasite modifies the features of life of its host, reducing its fitness, and overall, making every effort to make his life impossible. In short, it's a stress like any other. Again, we can say that the more you breed, the more likely to fall on the mutation that makes us strong. And besides, in the presence of parasites, it was noted that those that mutate most do best (2). Except that if you want to increase their chances of mutation breeding in addition, it is a bit in the process of shooting itself in the foot. For one simple reason, too: the more you are, the more it gives the parasite the ability to reproduce, and therefore, the more likely to pick ourselves a parasite. Besides, also in the case of bacteria, it was shown that the more one is divided, the sooner we help the parasite to do the same (3).
To summarize, we have a strategy that seems great advantage in case the stress is not alive, but becomes incredibly dangerous when the same becomes biotic stress. This is an example that highlights how the interaction with the environment and with other related species, and organisms grow in directions often very different.
Stress and the Evolution
Living in the city, a risk factor for anxiety?
This study by German and Canadian researchers confirms that many facets of urban life must be taken into account in mental health and that some areas of the brain associated with stress and anxiety are activated more in urban than rural . The research published in the online edition of the June 23 issue of Nature shows that live in the city is associated with higher activity in certain brain areas, but could not directly link this activity to the development and installation of social stress.
This research observed the brain activity in response to social stress among urban and rural populations. The study authors state that previous studies have shown that mental health problems, such as schizophrenia, anxiety and negative mood are more common among those who live or grow up in cities.
To test this theory, researchers at the University of Heidelberg in Germany and McGill University in Canada, volunteers exposed to negative verbal messages and asked them to solve puzzles while their brains were scanned by MRI, stress levels were assessed by measuring cortisol levels, heart rate and blood pressure were measured. Previous epidemiological studies have shown that the "urban" have a higher risk of psychological disorders including depression, schizophrenia and anxiety.
Living in the city was associated with higher activity in the amygdala, a brain region that reports of negative emotions and environmental threats. This area plays a very important role in anxiety disorders, depression and violent behavior. This activity is higher in the amygdala of the citizens. The increase in the activation of specific brain regions in response to social stress, can not be directly at this stage, linked to psychological disorders. In conclusion, brain activity differs between individuals high and living in urban vs. rural. These differences are identified in areas related to schizophrenia, anxiety and negative mood. But we can not determine why these differences in brain activity occurred and whether they are related to mental health problems or stress.
Stress anxiety ... how to act?
Relaxation therapy does not provide a systematic response to all anxiety disorders. But it can relieve or reduce a large number of events experienced in moments of crisis or anxiety.
Chronic anxiety and generalized anxiety is characterized by an excessively apprehensive. Relaxation therapy in the first place will help to manage the proactive type ruminations thoughts (which "run loop", regardless of their serious nature). Other techniques affect the attenuation of muscle tension and palpitations. Finally, exercises facilitate sleep, even when you are upset or worried.
Panic disorder ("panic attack" "anxiety attack") will be addressed in a management crisis, as soon as possible upstream. The premise felt by the subject often created a tense fast, which increases or accelerates the crisis. It is "the snake biting its tail."
Relaxation therapy techniques involved in prevention,calming breathing, conditioning a sign of relaxation (also called signal-sign). The person subject to these crises can also learn to manage dizziness, especially when it is in a public place.
As for the phobia, the sophrologist coordinates with that of the therapist following the "phobic". In fact, the phobia is often a mental mechanism of protection to an intense fear - fear being moved to another object (or situation), the more "mundane (e)". The principle here is rather "a train can hide another." Hence, if we "remove" the object, the risk of making up an excessive anxiety is unmanageable.
Once these prerequisites are installed, one can use techniques of habituation or "desensitization" as the gradual acceptance sophro-or-sophro sensory substitution.
Obsessive-compulsive disorder can be as a medical treatment. Relaxation therapy may respond to second-line globally to help the person relax (relaxation techniques classics like sophronisation base, for example).
Finally, the disorder post-traumatic stress will also be addressed initially on a medical or psychotherapeutic. In addition, relaxation therapy can have a very significant action on hyperactivity of the nervous system, providing about relaxation exercises both physical and mental. A re-education that is expected to positively stimulate the autonomic nervous system para-sympathetic (the regulation). The technique called "moving the sophro-negative" also helps to release tension and negative emotions associated with the traumatic event. Finally, this type of stress (often resulting from a collision, accident or injury) is accompanied by flashbacks ("images that run in a loop") that can be mitigated with the serial sophro-correction.
In summary, a large panel of technical exercises are quite adaptable to experienced anxiety, and easy to learn, and especially practice.
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