Many people with ME/CFS experience “orthostatic” symptoms when they stand up – including dizziness, altered vision, nausea and fatigue – which are caused by dysfunction of the autonomic nervous system.
In fact, an ME Research UK-funded study at Newcastle University in 2013 found that 13% of patients have a condition called postural orthostatic tachycardia syndrome (POTS), which is characterised by large changes in heart rate on standing, leading to palpitations, light-headedness and even fainting.
New research from the University of Toledo now provides evidence that POTS is an autoimmune disorder – that is, it stems from the body being mistakenly attacked by its own immune system.
Among 55 patients diagnosed with POTS, most had raised levels of autoantibodies against an adrenergic receptor, and more than half had raised anti-muscarinic receptor autoantibody levels. These changes were not seen in control subjects.
Adrenergic and muscarinic receptors are two of the main types of receptor in the autonomic nervous system, which controls heart rate and blood pressure among many other functions.
Of course, growing evidence also suggests that ME/CFS itself is an autoimmune condition, and several ongoing studies funded by ME Research UK are exploring this further, including those conducted by Prof. Scheibenbogen, Prof. Younger and Prof. Rincon.
As well as potentially revealing the pathology underlying POTS, the authors of the new study say that testing for these autoantibodies may provide an easy method for identifying the condition in a hospital setting. They also suggest that existing medications targeting the immune system could be an effective treatment for some patients, although more research is needed.