M. Boudarene, J.-J. Legros
Résumé. Le but de ce travail est d’étudier les processus psychologiques et biologiques qui sont impliqués dans la réponse de stress ; 40 sujets dont 21 femmes sont examinés. Leur âge moyen est de 42 +/– 12 ans. Tous consultent dans le cadre d’une clinique de stress et ne présentent aucun trouble psychique au moment de l’examen (critères DSM IV). L’épreuve expérimentale consiste à demander aux sujets d’accomplir des tâches cognitives simples : 1 – différencier deux types de stimulations auditives, 2 – éteindre le plus vite possible une lumière après un signal sonore avertisseur. L’anxiété-état, anxiété du moment, est évaluée à l’aide de l’inventaire de Spielberger (STAI). Les concentrations plasmatiques du cortisol et du DHEAs sont mesurées avant (t1) et après (t2) l’épreuve expérimentale. Les résultats montrent que les sujets présentent au moment de l’épreuve un état d’anxiété. Au-delà d’un certain niveau (« effet plafond ») l’anxiété n’augmente plus. La réponse à l’épreuve change de registre d’expression, le relais est pris par l’augmentation des concentrations plasmatiques du cortisol. Le DHEAs est également impliqué. L’accroissement de son taux plasmatique dépend de celui du cortisol comme le montre cette corrélation positive, r = 0,433, (p = 0,0033). L’augmentation isolée du cortisol est associée à une anxiété élevée tandis que celle du DHEAs est en relation avec une anxiété moins marquée. Un état anxieux intermédiaire est observé chez les sujets qui augmentent simultanément le cortisol et le DHEAs (p = 0,0225). Ces résultats suggèrent un probable effet bénéfique du DHEAs en rapport avec la diminution de l’anxiété, et une possible action antagoniste des deux stéroïdes. Mots-clés : Anxiété, Cortisol, DHEAs, Stress.
Study of the stress response : role of anxiety, cortisol and DHEAs Aim of the study – Several studies have exhibited the psychological processes that are implied in the stress response and have shown, according to Selye’s research, the participation of the hypothalamic-pituitary-adrenal axis and the major role of cortisol. The possible action of another adrenal steroïd, dehydroepiandrosterone (DHEA), is increasingly documented. The beneficial effect of the latter and his antistress role would be related to an antagonistic action to that of cortisol. The aim of our study was, first to assess biological and psychological aspects of the stress response, then to define the relationships that exist between these two processes. Population and methodology – 40 subjects (21 women) aged 42 +/– 12 years, who consulted within a « clinic of stress » (CITES Prevert, Liege, Belgium) were studied.
They all felt stressed but, according to DSM IV, were without mental disorders and drug free when examined. Subjects were asked to accomplish simple cognitive tasks : 1 – to distinguish two different auditory stimulations. The first one was a high-pitched sound of 1 470 Hz, which was presented unfrequently (20 %). The second one, a low frequency tone of 800 Hz, was presented more frequently (80 %). The interval between both stimuli was 1 s. The subject had to press a button when the rare stimulus was recognized. 2 – to extinguish a light after a warning tone of 64 dB, 50 ms and 1 000 Hz. The light, which followed one second later the tone, consisted of a series of flashes of 18 c/s that the subject had to stop by pressing a button. The purpose of this second procedure was that the subject was warned and had to prepare and anticipate the most rapid response. After that, subjects were submitted to self-evaluation psychological tests. The impact of psychosocial factors was assessed by Amiel-Lebigre life events questionnaire. Personality features and emotional response (state anxiety, related to experimental situation) were assessed by Spielberger inventory (STAI : State and Trait Anxiety Inventory). Psychological tests are practised immediately after experimental situation. Cortisol and DHEAs (dehydroepiandrosterone sulfate) were measured in blood samples taken before (t1) and after (t2) the experimental test. Cortisol was measured by radio-immunology and expressed as ng/ml of plasma. DHEAs was measured by radio-immunoassay and expressed as g/liter of plasma. Results and discussion – The majority of subjects displayed high scores of trait anxiety (37 subjects had a score > 42) and life events impact (35 subjects had a score > 200). These data confirmed that the subjects were fragile and were obviously stressed. In response to the cognitive tasks, that constituted for each subject a new event with which it was necessary to cope, 25 subjects exhibited high level of state anxiety (score > 42) and an increase of cortisol plasmatic concentrations occured solely in 11 persons. Ten among them were in the group of subjects which displayed a score of state anxiety > 42 (p = 0,0223, Chi square). Base on these data three types of stress response were identified : 1 – the experimental situation was experienced without anxiety (« psychological silence ») and without any increase in cortisol level (« biological silence »). There was no stress and these subjects were, despite their vulnerability, close to a « normal health state ». 2 – high emotional reaction (high level of state anxiety) was observed. This response reveals a psychological vulnerability that can be considered as the expression of a consecutive psychological distress induced by a threatening experimental situation. There were no biological manifestations (« biological silence »). 3 – high state anxiety and increased plasma cortisol levels were observed. The corresponding subjects were obviously more vulnerable. Conclusion – These results allow us to propose that the emergence of state anxiety is the first stress response and the « primary protest ». Up to a certain level, a plateau level, anxiety remains stable. Then, nature of the stress response changes and takes a biological aspect. Increased of cortisol plasma levels, the « secondary protest », is observed and gives evidence of an intensified and sustained stress response. Such a gradual phenomenon is particularly reported in elevated psychological distress which is associated with loss of control. It is important to note that identical scores of state anxiety (Mann Whitney test) were observed in anxious subjects with or without rise of plasma cortisol levels. DHEAs was also implied in the stress response. The enhancement of plasma levels of DHEAs were dependent on cortisol, as shown by the close correlation between both hormones (r = 0,433, p = 0,0033, Spearman test). The hypothesis of an antagonism between these two hormones is based on the fact that DHEAs opposes the action of cortisol and exerts a true anticortisol effect. This antagonism might be related to a competition in their synthesis and release by the adrenal gland. In the present case, high level of anxiety (state and trait) was associated with an increase of cortisol, while low level (of anxiety) was related to an exclusive rise of DHEAs. Intermediate anxious score was observed in subjects who showed increases of both cortisol and DHEAs (p = 0,0225, Kruskall Wallis test). Furthermore, a close relationship (negative correlation : Spearman test), was observed between increases in DHEAS and scores of state anxiety (r = – 0,382, p = 0,06) and trait anxiety (r = – 0,0097, p = 0,527). This means that the worriness and the underlying anxious ruminations and negative anticipations, which characterize trait anxiety, were less important in subjects who increased plasma DHEAs levels. In addition, emotional tension and uneasiness, which accompanies state anxiety, were also less marked. There are no studies reporting a relation between DHEA(s) and state or trait anxiety. Nevertheless, many authors have proposed a beneficial action of DHEA on the feeling of well-being. This beneficial role could be related to a double action of DHEA : a direct effect provided by its transformation into sexual hormones, an indirect one mediated by its competition with cortisol, of which the synthesis and consequently the activity decrease. L’Encéphale - N° 2 – Avril 2002
p. 139 – 146