title: Chronic fatigue syndrome: an update focusing on phenomenology and pathophysiology.
abstract: OBJECTIVE
  Chronic fatigue syndrome is a controversial condition especially concerning its clinical definition and aetiopathogenesis. Most recent research progress has been made in phenomenology and pathophysiology and we focused our review on these two areas.
  
  
  RESULTS
  The phenomenology research supports the notion of a discrete fatigue syndrome which can be distinguished from depression and anxiety. The current case definition, however, may need an improvement based on empirical data. Recent advances in understanding the pathophysiology of chronic fatigue syndrome continue to demonstrate the involvement of the central nervous system. Hyperserotonergic state and hypoactivity of the hypothalamic-pituitary-adrenal axis constitute other findings, but the question of whether these alterations are a cause or consequence of chronic fatigue syndrome still remains unanswered. Immune system involvement in the pathogenesis seems certain but the findings on the specific mechanisms are still inconsistent. Genetic studies provide some evidence of the syndrome being a partly genetic condition, but environmental effects seem to be still predominant and identification of specific genes is still at a very early stage.
  
  
  CONCLUSIONS
  The recent findings suggest that further research is needed in improving the current case definition; investigating overlaps and boundaries among various functional somatic syndromes; answering the question of whether the pathophysiologic findings are a cause or consequence; and elucidating the involvement of the central nervous system, immune system and genetic factors.
authors.affiliation: Department of Psychological Medicine, Institute of Psychiatry, King's College London, London, UK. h.cho@iop.kcl.ac.uk
authors.forename: Hyong Jin
authors.initials: HJ
authors.lastname: Cho
authors.forename: Anna
authors.initials: A
authors.lastname: Skowera
authors.forename: Anthony
authors.initials: A
authors.lastname: Cleare
authors.forename: Simon
authors.initials: S
authors.lastname: Wessely
mesh_terms: D001921:Brain / Q000378:metabolism / Q000503:physiopathology; D015673:Fatigue Syndrome, Chronic / Q000175:diagnosis* / Q000503:physiopathology*; D006801:Humans; D007030:Hypothalamo-Hypophyseal System / Q000378:metabolism / Q000503:physiopathology*; D010913:Pituitary-Adrenal System / Q000378:metabolism / Q000503:physiopathology*; D049268:Positron-Emission Tomography; D012701:Serotonin / Q000378:metabolism
chemical_list: D012701:Serotonin