Endocrine System
The hypothalamic-pituitary-adrenal axis (HPA axis) controls levels of hormones such as cortisol and is activated in a circadian rhythm and modulated by factors such as stress, digestion or illness. It is important in regulating energy metabolism, the immune system, stress responses and inflammation in the body.
The main endocrinological research findings in CFS are mild hypocortisolism, a blunted adrenocorticotropin (ACTH) response to stressors, and enhanced negative feedback sensitivity to glucocorticoids; however there is no specific or uniform dysfunction of the HPA axis in CFS and about half of relevant studies did not find evidence of either hypocortisolism or an abnormal response to various types of challenge tests. It has been debated whether these disturbances would play a primary role in the pathogenesis of CFS, but prospective evidence suggests that the HPA axis is not an important factor during the early stages of CFS, although it has been hypothesized that it might play a role in exacerbating or perpetuating symptoms later on in the course of the illness. A 2011 meta-analysis reported a small but statistically significant hypocortisolism in CFS. A study of cognitive behavioural therapy for CFS, which also measured cortisol levels, had observed that hypocortisolism was associated with a poorer response to CBT.
A 2006 update in the journal Current Opinion in Psychiatry stated, "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 (HPA axis) constitute other findings, but the question of whether these alterations are a cause or consequence of chronic fatigue syndrome still remains unanswered." Alterations in serotonin signaling can lead to physiologic and behavioral changes. Polymorphisms in genes related to serotonin pathways may indicate genetic predisposition in the pathophysiology of CFS. Some researchers think cold therapy can increase serotonin levels to treat CFS.
Read more about this topic: Pathophysiology Of Chronic Fatigue Syndrome
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