Fibromyalgia syndrome in women - a stress disorder? : Neurobiological and hormonal aspects

Sammanfattning: The FMS is almost exclusively a female disorder, as 90% of the patients struck by it are women. About 7% of all women in modern society have this disorder. The studies in this thesis demonstrated that variations in the female sex hormones over the menstrual cycle and in different hormonal states are important with respect to the severity of pain and other symptoms, global functioning and well being of FMS patients. The hormonal state is also of importance in the inter-connection with the monoaminergic systems, stress systems and pain processing systems. Besides the symptoms, this also appears as perturbed levels of neuropeptide Y (NPY), nociceptin and oxytocin in plasma.The importance of estrogen to pain processing peptides was shown in an animal study. In that study it was revealed that estrogen increase reduces pain sensitivity, and that estrogen is also able to change the levels of pain processing peptides such as substance P (SP) and met-enkephalin-Arg-Phe (MEAP) in certain brain areas, spinal cord and serum. It is suggested that stress may elicit pain through several neuroendocrinological mechanisms.All FMS patients scored higher than healthy women on mood and tension related symptoms, which is interpreted as an increased sensitivity and reaction to stress. FMS patients at the time of menstruation, and older, postmenopausal FMS patients were the most sensitive to these changes. The increased sensitivity to stress was also demonstrated in a personality study using the Temperament and Character Inventory (TCI), which showed that many female FMS patients are more anxious and worried and therefore also become easily fatigued.It is likely that development of the FMS is due to numerous biological events occurring in response to long-term stress. Women with stressful life experiences and anxious personality traits are probably more prone to develop this disorder, although various and sufficient stressful events of different origins can most likely lead to this disorder in any woman over the long run.