[From stressful life events to anxiety disorders].

Stress is usually defined on the basis of the consequences observed after a threatening environmental change. This type of definition is mainly attributable to Seyle who conceived stress reaction as a final pathway, related to numerous aggressions against physical or psychological integrity, and threatening homeostasis. On the other hand, different authors showed that aggression does not systematically leads to retroactive undoing, as some types of environmental modifications can provoke an increase of knowledge, enriching both coping style and adaptative processes. Life events can be considered as a neurohormonal activation following action, the activation process being strictly dependent on the suddenness and unexpectedness of the event. "Normal" (at times necessary) stress, allowing the adaptative and sometimes survival processes, has thus to be distinguished from pathological stress, which provokes suffering. Stressful life event is modifying the environment, and the subject has to mobilize all his capacity, specificity and defense style in order to cope with the new situation. In this view, stressful life events may provoke enrichment and reinforcement for some and severe anxious disorders for others. Numerous factors are involved in the deleterious effect of a stressful life event, explaining why the modalities of the answer are so dramatically variable between different subjects.