Salivary cortisol and posttraumatic stress reactions : methodological and applied studies before and after trauma
Sammanfattning: The field of psychotraumatology has its roots in ancient history. During the past decades, the surveillance of the psychobiological background of reactions to and consequences of traumatic stress has made great progress and the complexity of the human stress response system stands out. The hypothalamic-pituitary-adrenocortical axis activity, modulated by various neuroimmunological substances, seems to play a major role in the stress response. However, there are still inconsistencies in explanations of relationships between biological and psychological changes following traumatic stress. Moreover, the matter of predictive factors for the development of posttraumatic morbidity is still in a speculative phase.The aims of the present thesis were to further develop a commercial serum cortisol radioimmunoassay (RIA) for determination of cortisol in saliva and to test its reliability, specificity and sensitivity as a biochemical assay. The saliva sampling procedures and sample storage stability were also to be tested. Further issues were to investigate determinations of salivary cortisol and serum prolactin in relation to selfratings of posttraumatic psychological distress and general psychological health. Possible predictive and concurrent validity of salivary cortisol as a biochemical marker for posttraumatic psychological distress were to be tested.Cortisol is present in saliva mainly in non-protein form, representing the free, biologically active fraction of the total plasma cortisol concentration. In a first phase of the present thesis, the commercial serum cortisol RIA was modified for determination of cortisol in saliva. The relation between salivary and serum cortisol concentrations was tested. Reference ranges at 8 AM and 10 PM for the salivary cortisol assay were established from 195 healthy subjects. Salivary cortisol concentrations were tested in relation to serum cortisol in estimating adrenocortical function during endocrine dynamic function tests in 37 patients and 13 healthy controls. In testing salivary cortisol as a marker for stress for fieldwork use, a screening study was performed on 66 male rescue workers. Salivary cortisol at 8 AM and 10 PM and serum prolactin were determined and general psychological health and posttraumatic psychological distress were estimated with the self-rating scales General Health Questionnaire, Impact of Event Scale and Posttraumatic Symptom Scale. These scales were used in the second phase of the thesis. Three applied follow-up studies were performed with sampling of salivary cortisol and self-ratings: (a) a study of 31 UN-soldiers five days, two and nine months after a mine accident; (b) a study of 145 UN-soldiers before, at return, and two and six month after a six month mission. (c) a study of 101 UN-soldiers six and twelve months after a six month mission with severe combat exposure.The results from the present thesis indicate that the modified method of salivary cortisol determination possesses sufficient precision, accuracy, sample storage stability and procedural advantages for laboratory, clinical and field application. Moreover, it possesses moderate predictive information and moderate to high concurrent validity as a biochemical marker for posttraumatic psychological distress.
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