[Etiology of functional somatic syndromes].

Functional somatic syndromes are defined as several related syndromes that are characterized more by symptoms, suffering, and disability than by structural or functional abnormality. These syndromes include irritable bowel syndrome, tension-type headache, chronic fatigue syndrome, and fibromyalgia. Such syndromes have similarities in terms of definition, diagnosis, etiology, and treatment. To elucidate the pathogenesis of functional somatic syndromes, it is important to focus on gender-related factors, comorbidities of depression and anxiety, physiological responses like autonomic nervous function and hypothalamic-pituitary-adrenal axis, and patient-doctor relationship. Based on recent literatures, mood state and somatosensory amplification are suggested to play an important role in the psychopathological mechanism of functional somatic syndromes, and genetic and environmental factors need to be considered as well.