A new study on chronic fatigue syndrome (ME/CFS) suggests that an autoimmune reaction to the neurotransmitter serotonin damages serotonin-sensitive brain cells. Researchers also concluded that high levels of bacteria move through intestinal membrane in people with ME/CFS, which is known to play a role in autoimmunity.
Researchers compared serotonin antibodies in people with ME/CFS, those with chronic fatigue who don't meet ME/CFS criteria, and healthy controls. They found that autoimmune activity against serotonin was more than four times what it was in chronic fatigue, and twelve times higher than in healthy people.
Serotonin autoimmunity was linked to more severe hyperalgesia (pain amplification,) fatigue, brain fog, autonomic symptoms, sadness, and flu-like symptoms.
Researchers say serotonin autoimmunity could be part of the underlying pathology of the condition, and their results provide support for ME/CFS being a neuro-immune disorder.
What it Means
In autoimmunity, your immune system basically gets confused and identifies a healthy, normal part of your body as a foreign invader that should be destroyed. It then treats it like a virus or bacteria, creating specialized cells that seek it out and try to get rid of it. This response leads to inflammation and a host of other problems.
Serotonin has long been believed to play a role in ME/CFS. In your brain, it's a neurotransmitter, which means it transports certain messages from one brain cell to the next. In the rest of your body, it's a hormone. The highest concentration of serotonin is in your digestive system, where it plays important roles.
Another known factor of ME/CFS is chronic immune system activity. Bascially, it's in high gear all the time, as if it's fighting an active illness. Autoimmunity could help explain this.