Chronic Fatigue Syndrome and Negative HPA Axis Feedback
A recent study out of the U.K. suggests that the negative feedback loop of the HPA axis may be stronger in CFS patients than normal patients.
The HPA axis is a neuroendocrine system composed of the hypothalamus , pituitary , and adrenal gland. This system regulates many bodily processes such as the sleep cycle, the ability to deal with stress, and the immune system. In certain groups of CFS patients the HPA axis can become suppressed and the various symptoms of chronic fatigue syndrome can result.
When the body experiences a stressor (physical or mental), cortisol is released. Cortisol’s release is controlled by the hypothalamus, when it releases corticotropin releasing hormone, or CRH. The CRH the affects the pituitary gland and it releases adrenocorticotrophic hormone or ATCH. This ACTH then causes the adrenal glands to react to the stress and release cortisol from the adrenal cortex.
The amount of cortisol released by the body is controlled by a feedback loop that results from the interaction between the levels of cortisol and the hypothalamus and pituitary gland. In other words if the hypothalamus or pituitary gland sense that there is too much cortisol in the body, then they will not release as much CRH or ACTH.
In Chronic Fatigue patients this negative feedback loop may be overly sensitive. When the body is stressed and needs to produce more cortisol, the hypothalamus and pituitary gland are too sensitive to the cortisol and do not produce enough CRH or ACTH.
Why the HPA axis negative feeback loop in CFS patients is oversensitive is unknown. But as more studies show proof of physical abnormalities in Chronic Fatigue Syndrome patients. More funding for studies will be made available and some effective treatments may come about as a result.
